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Journée mondiale de la métrologie – 20 mai 2022

The theme this year is Metrology in the Digital Era. This theme was chosen because digital technology is revolutionizing our community and is one of the most exciting trends in society today. The adoption of digital technology is transforming metrology by improving processes and opening new opportunities.

World Metrology Day is an annual celebration of the signature of the Metre Convention on 20 May 1875 by representatives of seventeen nations, which marked the beginning of formal international collaboration in metrology. It is organized jointly by the Bureau International des Poids et Mesures (BIPM) and the International Organization of Legal Metrology (OIML) to recognize and celebrate the contribution of all the people that work in the field of metrology in intergovernmental and national metrology organizations and institutes throughout the year.

Further information on World Metrology Day, including video messages from the Directors of the two organizations, posters and a list of events, is available at:

Plan stratégique du BIPM 2022

Rapport BIPM-2022/03: Calibrant Assessment Guideline: Patulin

Published on 16 May 2022

Brochures sur le CIPM MRA publiées dans le cadre du programme CBKT du BIPM

A suite of brochures has been published under the auspices of the BIPM CBKT programme to provide information and assistance on key roles and mechanisms within the CIPM MRA. The brochures have been written in accessible way for both metrologists and non-experts alike.


CBKT publications


The suite of brochures explain the benefits of the CIPM MRA as well as giving an overview of its mechanisms. The suite includes six individual inserts that give details of:

  • participation and coordination within the CIPM MRA
  • metrological traceability
  • comparison activities
  • calibration and measurement capabilities within the CIPM MRA
  • CIPM MRA review processes
  • quality management.

The suite of brochures are available online and hard copies are available from the Regional Metrology Organization secretariats or directly from the BIPM CBKT office.

We hope these CBKT brochures will equip those who are interested or involved in CIPM MRA activities with a comprehensive overview of all the essential elements.

CBKT Team.

The BIPM offers its thanks to NIST (USA) for providing the funds, via the CBKT programme, to prepare the suite of brochures. The content was prepared by Douglas A. Olson (NIST and former JCRB Executive Secretary) and Olav Werhahn (PTB), the current JCRB Executive Secretary, with input from Chingis Kuanbayev (BIPM) and Andy Henson (BIPM).


Prix Marcel Ecabert 2022 décerné à Gérard Petit

Dr Gérard Petit from the BIPM Time Department has been awarded the 2022 Marcel Ecabert Award by The European Frequency and Time Forum (EFTF). The citation recognised his “long-standing involvement and key contributions in the timing activities of the BIPM and more generally in International time and frequency metrology."

The EFTF Marcel Ecabert Award is a lifetime award and honours the excellent achievements of the recipient in the field of time and frequency. It is named after the late Marcel Ecabert, founding member of the EFTF and member of its Executive Committee.

The awards ceremony took place at the 2022 joint conference of the EFTF and the IEEE International Frequency Control Symposium (IEEE IFCS), which was held on 24-28 Apr 2022 at the Cité des Sciences et de l'Industrie, Paris (France). The joint congress was held in-person for the first time in 3 years, gathering together more than 400 people.

The BIPM joins in congratulating Gérard for his long and fruitful involvement in time metrology research and development.

Stop squandering data: make units of measurement machine-readable - Article dans Nature

L'ISO signe la déclaration commune d'intention sur la transformation numérique au sein de l'infrastructure internationale scientifique et de la qualité

The International Organization for Standardization (ISO) signed the Joint Statement of Intent On the digital transformation in the international scientific and quality infrastructure on 12 April 2022. The joint statement had previously been signed by the BIPM, the International Organization of Legal Metrology (OIML), the International Measurement Confederation (IMEKO), the International Science Council (ISC) and its Committee on Data (CODATA) on 30 March 2022.

The joint statement provides a platform for the signatory organizations to come together to indicate their support, in a way appropriate to their particular organization, to the development, implementation, and promotion of the SI Digital Framework as part of a wider digital transformation of the international scientific and quality infrastructure. The addition of ISO further strengthens the collaboration and global reach of the initiative. Sergio Mujica, ISO Secretary-General, commented that “Organizations in the International Quality Infrastructure must continue to transform to further embrace digitalization. ISO is fully committed to achieve further digitalization of standardization and we are working hard to implement our joint programme with the IEC on Standards Machine Applicable, Readable and Transferrable (SMART). The design and implementation of the SI framework will accelerate the positive changes in the ecosystem. Measurement is also an important topic for ISO, for example, when it comes to testing and conformity assessment. ISO will continue bringing its contribution, supported by the work performed by BIPM, to build the needed digital standards infrastructure of the future.

The joint statement is part of an ongoing initiative by the International Committee for Weights and Measures (CIPM) and its Task Group on the Digital SI (CIPM-TG-DSI) to develop and establish a world-wide uniform and secure data exchange format based on the International System of Units (SI).

Signing of the Joint Statement of Intent by Sergio Mujica, ISO Secretary-General.

Formation BIPM-SIM sur la KCDB 2.0

The BIPM-SIM Training course: KCDB 2.0 was held on 20-22 April 2022 and welcomed more than 160 participants from 20 countries over the three days. The online course was organized for member NMIs and DIs of the Inter-American Metrology System (SIM).

The three-day (3.5 hours/day) online training course was designed to deliver information for those who: write CMCs in the KCDB; review the CMCs; pilot comparisons; and for TC/WG Chairs who operate the CIPM MRA processes. The programme was organized to cover three main topics:

  1. CIPM MRA Environment
  2. Intra-RMO review of CMCs
  3. JCRB review of CMCs

The content was delivered following a logical sequence, starting from the CIPM MRA requirements, and including case studies on how these requirements were implemented, practical exercises and discussions. The practical exercises were sent to registered participants one week ahead of the training course, so that they could follow the exercises and practice in advance if they wished. The practical exercises were organized using the KCDB CBKT training platform. Participants had opportunities to write CMCs directly on the training platform, review CMCs, register comparisons, and act as a TC/WG Chair for the exercises.

Comments from participants:

“….I’d like to compliment your use of pre-class preparation exercises and active learning pedagogy.”

“…thank very much for organizing this training. It was nice to have the possibility to try live on the KCDB CBKT training platform”.

“…This has been a great training event for SIM”.


Participants in the BIPM-SIM Training course: KCDB 2.0.


Rapport de la 30e réunion du CCT (2022)

Publié le 25 avril 2022

Appel d'offres : Achat d'un analyseur de dioxyde de carbone et de méthane

Signature d’une Déclaration commune d’intention sur la transformation numérique au sein de l'infrastructure internationale scientifique et de la qualité

The BIPM, the International Organization of Legal Metrology (OIML), the International Measurement Confederation (IMEKO), the International Science Council (ISC) and its Committee on Data (CODATA) signed a Joint Statement of Intent On the digital transformation in the international scientific and quality infrastructure on 30 March 2022. The joint statement provides a platform for the signatory organizations to come together to indicate their support, in a way appropriate to their particular organization, to the development, implementation, and promotion of the SI Digital Framework as part of a wider digital transformation of the international scientific and quality infrastructure. Other international organizations are expected to sign the joint statement in the future.

The joint statement is part of an ongoing initiative by the International Committee for Weights and Measures (CIPM) and its Task Group on the Digital SI (CIPM-TG-DSI) to develop and establish a world-wide uniform and secure data exchange format based on the International System of Units (SI). Prof. J. Ullrich, Chair of the CIPM-TG-DSI, commented that the signing of the joint statement marks a ground-breaking step in transforming the highly successful international scientific and quality infrastructure, with the SI as an anchor of trust, into the era of digitalization.

To further reinforce the CIPM’s commitment to the digital transformation, Draft Resolution B On the global digital transformation and the International System of Units will be presented to the 27th meeting of the General Conference on Weights and Measures (CGPM) in November 2022.

Signing of the Joint Statement of Intent. Clockwise from top left: Wynand Louw, CIPM President (on behalf of the BIPM); Mathieu Denis, ISC Science Director and Acting CEO; Barend Mons, CODATA President; Roman Schwartz, CIML President (on behalf of the OIML); Frank Härtig, IMEKO President.

Webinaire du CCRI “Git for Metrology”

The BIPM hosted a webinar in March 2022 on the topic of Git for metrology, with a focus on the “git” free software, which is widely used for “version control” in software development.

The webinar was organized by the Consultative Committee for Ionizing Radiation (CCRI) and attracted more than 250 participants. It is now available from the BIPM YouTube channel.

It included five speakers who gave an overview of how version control promotes best practices in file management and why metrology is a field particularly suited to the adoption of its principles. It introduced version control using a methodology that originated in software development and which provides tools for the management of any document or project. The webinar included two case studies of metrology projects that are managed successfully using git.

The speakers were:

  • Massimo Pinto (ENEA-INMRI, Italy) who gave an overview of software version control and its potential for personal and collaborative use.
  • Frédéric Tessier (NRC, Canada) presented the philosophy behind version control and proposed a ‘fundamental mental picture’ to accelerate git learning.
  • Reid Townson (NRC, Canada) demonstrated how to get started with git, create a repository and start making ‘commits’.
  • Romain Coulon (BIPM) presented a case study using git and GitHub in the BIPM Ionizing Radiation Department to ensure version control of the database for key comparisons in radionuclide metrology.
  • Frédéric Meynadier (BIPM) presented the application of GitLab in the BIPM Time Department and how it is used for collaboration with external colleagues, internal development of core software, and personal projects.

Nouvel Associé à la CGPM : Cambodge

Le Royaume du Cambodge est devenu Associé à la CGPM le 1er janvier 2021.​​​​​​​

De nouveau Associé à la CGPM : Zimbabwe

La République du Zimbabwe est à nouveau devenue Associé à la CGPM le 8 février 2022.

Nouvel État Membre : Maroc

Le Royaume du Maroc est devenu État Membre le 24 mai 2019

Nouvel État Membre : Équateur

L’Équateur, Associé à la CGPM depuis 2000, est devenu État Membre le 6 août 2019.

Nouvel État Membre : Estonie

L'Estonie, Associée à la CGPM depuis 2005, est devenue État Membre le 19 janvier 2021.

JCTLM Database Newsletter (2022)

Stéphane Solve nommé secrétaire exécutif du CCT

Dr Stéphane Solve has been appointed as the Executive Secretary of the Consultative Committee for Thermometry (CCT). He took over the role from Dr Susanne Picard, who stepped down as Executive Secretary at the end of the 30th meeting of the CCT in February 2022.

Stéphane is a physicist in the Electrical Metrology area of the BIPM Physical Metrology Department with a background in thermometry, including having worked on the CCT-K7 comparison of water triple point cells, piloted by the BIPM.

The CCT President, Dr Yuning Duan, and the BIPM Director, Dr Martin Milton, thanked Susanne at the CCT meeting for her invaluable contributions since 2014 and welcomed Stéphane into the role.

Carine Michotte élue vice-présidente de l'ICRM

Carine Michotte, a Physicist in the BIPM Ionizing Radiation Department, was elected as a Vice-President of the International Committee for Radionuclide Metrology (ICRM) on 15 June 2021, along with Raphaël Galea, NRC (Canada). The ICRM Executive Board is composed of the President, three Vice-Presidents and the Secretary.

Carine coordinates the SIR activity comparisons with the Ionizing Radiation Department’s radionuclide metrology group and led the development of the SIRTI. She has travelled to 14 different NMIs from five RMOs to run SIRTI activity comparisons of short-lived radionuclides, which are of major importance in nuclear medicine.

Carine has been involved in the activities of the ICRM since 1997, participating in ICRM conferences and working group meetings. She is a member of the Programme Committee and Scientific Committee for the ICRM 2023 conference that will take place in Bucharest (Romania).

Atelier 2022 “Rôle de la métrologie dans la lutte contre le changement climatique” : inscriptions et appel à communications

Appel à candidatures pour le CIPM

Transfert de connaissances via Metrologia

Webinaire du CCRI "Git for Metrology" - vidéo disponible

Rapport BIPM-2022/02: Units and values for the ozone absorption cross section at 253.65 nm (air)

Published on 10 March 2022

Prolongement de l'initiative CBKT commune au BIPM et à TÜBİTAK UME

The BIPM is pleased to announce the extension of the joint initiative “BIPM–TÜBİTAK UME project placements” for another two cycles, which will be delivered in 2022 and 2023. This extension follows the success of the previous four cycles.

This initiative, organized by the BIPM and the National Metrology Institute of Turkey (TÜBİTAK UME), is designed to provide opportunities for metrologists to gain in-depth knowledge and experience by conducting research on a subject of their interest in TÜBİTAK UME's laboratories. In addition, participants are able to expand their understanding of the international aspects of metrology through intensive CIPM MRA e-learning opportunities and seminars.

Over four cycles of this initiative (from 2018 to 2021), the BIPM and TÜBİTAK UME have hosted thirty-seven talented metrologists from twenty-four countries for a period of 1 to 3 months at the TÜBİTAK UME laboratories. The reports received from the participants on completion of their placements have demonstrated that the projects were an extremely valuable method of knowledge transfer. The research projects have covered a diverse range of subjects from decreasing the uncertainty of measurement standards through to expanding metrological capabilities in the laboratory to underpin scientific activities, healthcare, and industry.

Participants and their mentors in the cycle four placements at the TÜBİTAK UME laboratories.


One of the key elements of this initiative is tailoring of the knowledge transfer activities to the needs of the participants. The selected participants submit their projects of interest, and based on this information, the research plan and the duration of the placement are identified before their arrival. The participants are supported by mentors from TÜBİTAK UME during their placements. This formula undoubtedly maximizes the knowledge transfer, and thus we would like to acknowledge the valuable support from the scientists of TÜBİTAK UME.

We would like to offer our sincere thanks to TÜBİTAK UME (Turkey) for this joint initiative, and the valuable contribution towards strengthening the BIPM Capacity Building and Knowledge Transfer (CBKT) Programme.

The call for applications for cycle five, to be run in 2022, will be opened soon, and the registration link will be sent to RMOs in due course.

Feedback from previous cycles:

I would like to thank BIPM and TÜBİTAK UME for providing the great opportunity in training programme, and NIMT for funding support. I would like to express gratitude my tremendous mentor, Dr Muslum Akgoz, head of Bioanalysis Laboratory, who gave brilliant comments and suggestions for me. A special thanks to Dr Burhanettin Yalcinkaya for always support and assistance me not only in the laboratory experiments but also in living life in Turkey. I am also very grateful to all who have contributed to the works and co-workers (Bioanalysis team, UME), thanks for all the helpful advice during this period and for creating a very good working environment.

Dr Sasithon Temisak, NIMT (Thailand).

Rapport de la 13e réunion du CCAUV (2021)

Publié le 7 mars 2022

Journée mondiale de la métrologie de 2022 : La métrologie à l'ère numérique

The 2022 World Metrology Day Resource Website is now live. The theme this year is Metrology in the Digital Era.

This theme was chosen because digital technology is revolutionizing our community and is one of the most exciting trends in society today. The adoption of digital technology is transforming metrology by improving processes and opening new opportunities.

World Metrology Day is an annual celebration of the signature of the Metre Convention on 20 May 1875 by representatives of seventeen nations. It is organized jointly by the Bureau International des Poids et Mesures (BIPM) and the International Organization of Legal Metrology (OIML) to recognize and celebrate the contribution of all the people that work in intergovernmental and national metrology organizations and institutes throughout the year.

Each year World Metrology Day is prepared in collaboration with one of the Regional Metrology Organizations. The poster for 2022 was designed under the auspices of COOMET by the NSC “Institute of Metrology” (Ukraine).

Further information on World Metrology Day, including a message from the Directors of the two organizations, posters, and a list of events, is available at:

Procès-verbaux de la 109esession du CIPM (2020)

Décisions du CIPM (octobre 2021)

Décisions du CIPM (juin 2021)

Procès-verbaux de la première partie de la 110esession du CIPM (2021)

Projets de résolution - 27e réunion de la CGPM (2022)

Published on 1 February 2022

Procès-verbaux de la seconde partie de la 110e session du CIPM (2021)

JCTLM Database Newsletter (2020) Special Report

JCTLM Database Newsletter (2020)

JCTLM Database Newsletter (2021) Special Report

JCTLM Database Newsletter (2021)

Rapport BIPM-2022/01: BIPM SRPs upgrade 2021

Published on 17 February 2022

Le JCTLM vous souhaite une excellent Journée mondiale de la métrologie 2021 !

The Joint Committee for Traceability in Laboratory Medicine (JCTLM) is celebrating World Metrology Day on 20 May 2021 through a series of videos on measurements in laboratory medicine. The theme this year is “Measurement for Health”.

Watch the videos on measurements in Laboratory Medicine for broader perspectives on the importance of metrological traceability in laboratory medicine for individual patients and for risk assessments in populations.

Watch the videos on measurements in laboratory medicine



Pages internet de la 27e réunion de la CGPM (2022)

Les pages internet consacrées à la 27e réunion de la CGPM, qui se tiendra du 15 au 18 novembre 2022, sont désormais disponibles et comprennent notamment la convocation, les projets de résolution et un programme provisoire. Ces pages seront mises à jour régulièrement afin de présenter les informations et documents les plus récents. Les parties prenantes pourront se tenir informées de la préparation de la CGPM en consultant les rubriques « Actualités » et « Rapports et annonces » du site internet du BIPM ou en recevant les « BIPM eNews ».

Compte tenu des restrictions de voyage sans précédent qui ont été mises en place en raison de la pandémie de COVID-19, il est très peu probable que l’ensemble des États Membres puissent être représentés en personne à la 27e réunion de la CGPM. C’est pourquoi le CIPM a reconnu que la réunion devrait se tenir dans un format hybride, permettant à la fois une participation en personne et à distance. Le CIPM a rédigé une « Procédure spéciale » afin de mettre en place les mesures nécessaires pour organiser une réunion hybride. Le texte proposé à ce sujet est également disponible sur les pages internet consacrées à la CGPM.

La réunion de la CGPM se tiendra au Palais des Congrès de Versailles.

BIPM e-learning platform expanded to allow RMOs to publish their training material

The BIPM has expanded its e-learning platform to allow RMOs to publish their training material on the site, complementing the BIPM material. The aim of the BIPM e-learning platform is to facilitate online training and assistance to increase the effectiveness of the world-wide coordinated metrological system. 

This initiative will enable cross-RMO access to courses, increasing the suite of materials available and reducing the likelihood of developing duplicate material. Over time it will encourage the delivery of knowledge in a coordinated way, as well as facilitating joint development of courses.

The e-learning platform was launched in April 2021 with four courses related to the scientific activities of the BIPM and the CIPM MRA mechanisms. Since its launch more than 400 metrologists from the global NMI and DI community have participated in the open and restricted access courses available on the platform. The platform is accessible around the clock and is optimized for desktop and handheld devices to provide learning support to metrologists as conveniently as possible.

Driven by the initial success of the platform, the BIPM explored the possibility of expanding its capabilities to host RMO e-learning material. The RMOs responded positively to this proposal and indicated their intention to join the initiative. This initiative meets the requirements outlined in the BIPM Strategic Plan (2018) which states “…To work towards a long-term integrated “training platform” shared between the BIPM and the RMOs…

The update was tailored to the needs of the RMOs, and the newly created ‘RMO Sectors’ allow them to appoint/assign their course creators, create courses and enroll participants, as well as generating reports on the e-learning courses.

Participation in this initiative requires signing of a formal arrangement between the BIPM and RMOs to ensure the ongoing reliability of the e-learning platform and publication of up-to-date material.

Signing of the practical arrangement with the BIPM. Clockwise from top left: Valery Hurevich, COOMET President; Jörn Stenger, EURAMET Chairperson; Martin Milton, BIPM Director; Amina Hassan Al Bastaki, GULFMET President.

As of today, EURAMET, COOMET and GULFMET have signed the practical arrangement with the BIPM. This formal step will be followed by training of RMO course creators on the mechanics of producing interactive learning courses. It is hoped that RMO course content will be available within the first half of 2022. Discussions are at various stages with the other RMOs.

We would like to offer our sincere thanks to METAS (Switzerland) who sponsored the extension of the BIPM e-learning platform and training for the RMOs that have joined the initiative.

The extended platform is available at: The RMO Sectors will be made live as soon as the arrangements are agreed, and material is made available. New courses that are posted on the platform will be announced in due course.

Nouvel État Membre : Bélarus

La République du Bélarus, Associée depuis 2003, est devenue État Membre le 13 janvier 2020.

Nombre record d'étalons de fréquence contribuant au calcul du Temps atomique international

International Atomic Time (TAI) achieves its stability from more than 450 atomic clocks world-wide and its accuracy from a small number of primary and secondary frequency standards which aim at realizing the SI second with the smallest uncertainty. Each month the BIPM publishes, in section 3 of Circular T [1], an estimation of the TAI frequency accuracy as measured by those individual frequency standards, as well as an ensemble average computed by the BIPM. In November 2021, sixteen different frequency standards operated in eleven laboratories contributed to this estimation, including ten Cs fountains, one Rb fountain, one Sr optical lattice and two Yb optical lattice clocks, in addition to the two legacy Cs beams operated by the PTB. This constitutes a record level of participation, both in terms of the number of different standards and the number of different laboratories.

Optical clocks have reached a proven accuracy of order 10−18 in relative frequency, surpassing the present Cs fountains by two orders of magnitude and driving the Consultative Committee for Time and Frequency (CCTF) to initiate work towards a redefinition of the second [2]. The CCTF has set-up a wide-ranging task force of experts, which worked to define a number of mandatory criteria to be achieved before changing the definition. One of the mandatory criteria states that optical standards should regularly contribute to TAI, with a goal of at least three contributions per month, with a total uncertainty not larger than 2 × 10−16. This criterion is intended to ensure that the accuracy of TAI is at least maintained and hopefully improved when the redefinition takes place and that it will be based on a robust set of optical frequency standards. Indeed after redefinition Cs fountains will become secondary standards with enlarged uncertainty while the uncertainty of optical standards will be reduced and it is important to ensure that the overall effect of the change is beneficial to TAI.

In 2021, 13 evaluations of optical frequency standards could be used to calibrate TAI, this is more than twice as many as the total number in the preceding three years (PSFS chart). Furthermore, two of them had a total uncertainty around 2.5 × 10−16, which is close to the requirement set in the criterion for redefinition. While this is only a first step towards achieving one of the mandatory criteria, this shows the strong impetus from NMIs and DIs to operate optical frequency standards and move towards the redefinition. The results show significant progress in the operational capabilities, with optical clock uptime exceeding 90 % in some cases. This allows longer operating period and reduced frequency transfer uncertainty, key factors to achieve contributions of optical standards to TAI with a total uncertainty not larger than 2 × 10−16 as required. Looking at the past history of Cs fountain development (PSFS chart) we expect that a similar trend will occur for optical standards, so that the redefinition of the second could take place in 2030 as in the current CCTF plans.

Contact Gérard Petit for more information.


Sr optical lattice clock (image courtesy of NICT)


Yb optical lattice clock (image courtesy of KRISS)


Yb optical lattice clock (image courtesy of NMIJ)




Peigne de fréquence du BIPM installé avec succès dans le laboratoire des longueurs du CENAM

CENAM (Mexico) has successfully installed a frequency comb, which was built and operated by the former BIPM Length Section’s laser laboratory.

The equipment installed by CENAM is the second of two frequency combs that were identified as being worth offering to NMIs for use in their work programmes, following the dismantling of the former BIPM Length Section’s laser laboratory. Information about the frequency combs was circulated among the NMIs after consultation with the Consultative Committee for Length (CCL). The first comb was successfully installed by INTI (Argentina) in 2019. The two frequency combs had originally been built by the BIPM and are used in comparing microwave to optical frequency radiations.

The second comb has been installed in the CENAM frequency comb laboratory and initial tests were carried out at the end of 2021. The tests proved that each of the systems is operating correctly, and an optical supercontinuum was generated. The CENAM length group expects to start using the frequency comb to provide calibration services, mainly to dimensional metrology laboratories, in the second quarter of 2022.

The installation of the former BIPM frequency combs by CENAM and INTI demonstrates the successful transfer of equipment, developed by the former BIPM Length Section, and which is now being used to support length metrology in different NMIs.

The BIPM offers its best wishes to the CENAM length group for the new activity.

The former BIPM frequency comb installed in the CENAM length laboratory

États Membres et États et entités économiques associés

Depuis le 8 février 2022, le BIPM compte 63 États Parties à la Convention du Mètre ("États Membres") et 40 États et entités économiques associés.


États Membres Associés

Rapport annuel du BIPM 2020/2021

Published on 13 July 2021

Calcul des contributions des États Membres

Notification 2022

Arrangement de reconnaissance mutuelle du CIPM

L'Arrangement de reconnaissance mutuelle du CIPM (CIPM MRA) est la structure permettant aux laboratoires nationaux de métrologie de démontrer l'équivalence internationale de leurs étalons de mesure et des certificats d'étalonnage et de mesurage qu’ils émettent.

Le CIPM MRA assure ainsi la reconnaissance internationale des aptitudes en matière de mesures et d'étalonnages (CMCs) (examinées et approuvées par les pairs) des laboratoires participants. Les CMCs, une fois approuvées, sont publiées dans la base de données du CIPM MRA (KCDB), qui contient également d'autres informations techniques sur les comparaisons effectuées.


Au sujet de la KCDB

Système international d'unités (SI)

Le SI est le système pratique d'unités de mesure recommandées.

Depuis l'adoption historique de la Résolution 1 par la CGPM en 2018, toutes les unités du SI sont définies à partir de constantes de la nature, ce qui permet d'assurer la stabilité du SI dans le futur et ouvre la voie à l'utilisation de nouvelles technologies, y compris celles quantiques, pour mettre en pratique les définitions.


Définitions des unités


Renforcement des capacités et transfert des connaissances

Le Programme du BIPM de renforcement des capacités et de transfert des connaissances (CBKT) a pour objectif d’accroître l’efficacité de la participation des États Membres et Associés au système métrologique mondial coordonné.

En 2020, le programme CBKT du BIPM a été enrichi avec le lancement d'une plateforme d'apprentissage en ligne destinée au personnel des laboratoires nationaux et désignés des États Membres et Associés. Cette plateforme propose des cours spécifiques sur les activités de la métrologie scientifique, notamment sur les mécanismes du CIPM MRA. Le développement de la plateforme se poursuit afin d'offrir la possibilité d'héberger du contenu pour les organisations régionales de métrologie.

Programme CBKT du BIPM

Rapport de la 18e réunion du CCM (2021)

Published on 11 January 2022

Mission, rôle et objectifs

Le BIPM est l'organisation intergouvernementale créée par la Convention du Mètre ; ses États Membres agissent en commun en ce qui concerne les sujets liés à la science des mesures et aux étalons de mesure.


Notre vision est d'être universellement reconnu comme l'organisation de référence internationale concernant le système mondial de mesure.


Notre mission est de travailler au niveau international avec les laboratoires nationaux de métrologie de ses États Membres, les organisations régionales de métrologie, ainsi que ses partenaires stratégiques, et de tirer parti de son statut d'organisation internationale et impartiale pour promouvoir et faire avancer la comparabilité mondiale des mesures pour :

  • la découverte et l'innovation scientifique,
  • la production industrielle et le commerce international,
  • l'amélioration de la qualité de vie et la préservation de l'environnement.


  • Représenter la communauté métrologique internationale afin d'en maximiser la reconnaissance et l'impact.
    • Nous coopérons avec les organisations intergouvernementales pertinentes ainsi qu'avec d'autres organismes internationaux afin de développer les possibilités de tirer parti de la métrologie pour relever les défis mondiaux.

  • Être un centre de collaboration scientifique et technique entre les États Membres, leur permettant de développer des aptitudes pour les comparaisons internationales de mesure, sur le principe des frais partagés.
    • Nous coordonnons des comparaisons internationales des étalons de mesure nationaux considérées comme de la plus haute priorité.
    • Nous établissons et maintenons des étalons de référence appropriés utilisés pour conduire, au plus haut niveau métrologique, des comparaisons clés internationales et assurons des étalonnages dans le cadre de ces comparaisons.

  • Coordonner le système mondial de mesure, en garantissant la comparabilité et la reconnaissance au niveau international des résultats de mesures obtenus.
    • Nous coordonnons des activités entre les laboratoires nationaux de métrologie des États Membres et les organisations régionales de métrologie, notamment en proposant des services techniques en soutien au CIPM MRA et en fournissant l'infrastructure nécessaire au développement et à la promotion du SI.

Notre mission et nos objectifs du BIPM sont étayés par notre travail dans les domaines suivants :

  • le renforcement des capacités, avec pour objectif de parvenir à un équilibre global des aptitudes métrologiques des États Membres ;

  • le transfert de connaissances, qui permet de garantir que le travail du BIPM a le plus grand impact possible.

Compendium des principales règles et pratiques applicables au BIPM

Calcul des souscriptions des Associés

Bonne Année !

Le Bureau International des Poids et Mesures vous présente ses meilleurs vœux pour la Nouvelle Année


400e publication de la Circulaire T par le BIPM en 2021


L’expérience scientifique et artistique « Équation du temps »
a été créée par Raphaël DALLAPORTA en collaboration avec des chercheurs
du LNE-SYRTE à l’Observatoire de Paris - PSL.
Cette photographie est reproduite avec leur permission.

L’image du Soleil photographiée pendant une année à l’Observatoire de Paris - PSL illustre « l'équation du temps ». Cette expérience met en évidence les différences de temps entre la période de 24 heures indiquée par les horloges et la durée d’une journée fondée sur l'observation du Soleil au midi moyen.

Au 20e siècle, la mesure du temps est passée des observations astronomiques aux mesures effectuées à l’aide d’horloges atomiques et le Bureau international des poids et mesures (BIPM) a été chargé de calculer le Temps universel coordonné (UTC).

En avril 2021, le BIPM a célébré la 400e publication mensuelle des valeurs de référence de l’UTC dans sa Circulaire T.

Cette coopération internationale de plus de 85 laboratoires nationaux de métrologie permet de coordonner la dissémination des signaux de temps et de fréquence de référence dans le monde entier.

Rapport de la 18e réunion du CCL (2021)

Publié le 15 décembre 2021

Rapport financier 2020

Atelier JCTLM-ICHCLR-IFCC : les inscriptions sont ouvertes

The Workshop on overcoming challenges to global standardization of clinical laboratory testing: reference materials and regulations, will be held on-line from 6 to 10 December 2021.

This workshop is being organized jointly by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Scientific Division, the International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR) and the Joint Committee for Traceability in Laboratory Medicine (JCTLM).

Participation is open to those in the field of clinical laboratory testing and related activities, including regulatory requirements and global standardization.

On-line registration can be made from HERE

The aim is the workshop is to develop and publish recommendations on how the laboratory medicine community can address challenges related to reference materials and to country and region-specific regulations to achieve standardized results more effectively on a global basis.

An outline of the programme is: 
Session 1: What are the needs and logistical challenges for standardized results?
Session 2: What are the challenges for CRM producers?
Session 3: What are the challenges to meet regulatory requirements in different countries or regions?
Session 4: Develop workshop recommendations for publication and follow up actions

Details of the programme and time for each session of the workshop can be found at:

Rapport de la 25e réunion du CCU (2021)

Published on 17 November 2021

Webinaire du JCGM/WG2 sur le VIM4 : vidéo disponible

The video of the JCGM/WG2 VIM4 Webinar is now available on the BIPM YouTube page. The webinar gave an overview of the Committee Draft of the new edition of the International Vocabulary of Metrology (VIM4).

More than 400 attendees watched the webinar, which was held on 6 May 2021. The panel gave presentations on the Joint Committee for Guides in Metrology (JCGM) and its Working Group 2 (WG2 - VIM Committee); the VIM4 Committee Draft; the significant changes between the VIM3 and the VIM4; and the new entries on nominal properties.

The presentations given at the webinar are available on the VIM4 webinar webpage

Metrology for Clean Air : lancement d’un programme en ligne de transfert des connaissances sur l’utilisation de la méthode FTIR pour la caractérisation des étalons de gaz

38e édition des Journées européennes du Patrimoine au BIPM


The BIPM opened its doors to the public for the second time on Saturday 18 and Sunday 19 September 2021 for the 38th Journées européennes du Patrimoine (European Heritage Days). The open days attracted 215 participants, who were given a guided tour of the Pavillon de Breteuil, the BIPM collection of historical instruments and the garden.

The European Heritage Days were launched in France in 1985. The Programme has been a joint initiative of the Council of Europe and the European Union since 1999.

Le BIPM ouvrait ses portes au public pour la deuxième fois, samedi 18 et dimanche 19 septembre 2021, à l'occasion des 38es Journées européennes du Patrimoine. Ces journées portes ouvertes ont attiré 215 participants pour une visite guidée du Pavillon de Breteuil, de la collection d'instruments anciens du BIPM et du jardin.

Les Journées européennes du patrimoine ont été lancées en France en 1985. Ce programme est une initiative conjointe du Conseil de l'Europe et de l'Union européenne depuis 1999.

Metrologia - Review of field characterization techniques for high-intensity therapeutic ultrasound

Journée mondiale de la normalisation (14 octobre 2021) : "Une vision commune pour un monde meilleur"

Metrologia - A review of approaches for the practical realization of traceable length metrology from 10−11 m to 1013 m

Rapport de la 32e réunion du CCEM (2021)

Published on 8 November 2021.

Metrologia: Focus on Length Metrology

Metrologia: Focus on Realization, Maintenance and Dissemination of the Kilogram

Principes gouvernant la photométrie (2e édition), BIPM/CIE

Publié le 16 mai 2019.

Décisions prises lors de la 43e réunion du JCRB (2021)

Signature du CIPM MRA par M. Mohammed Berrada, directeur du LPEE-LNM (Maroc)

On 15 July 2019 the BIPM hosted a visit by a delegation from the Kingdom of Morocco composed of representatives from the Ministère de l'Industrie, de l'Investissement, du Commerce et de l'Economie Numérique and the Laboratoire national de métrologie, Laboratoire public d'essais et d'études (LPEE-LNM). The visit was joined by representatives from the BIPM, LNE, PTB (project coordinator for the Maghreb) and the BIML.

Dr Martin Milton, Director of the BIPM, welcomed the delegation and congratulated the Kingdom of Morocco on its recent accession to the Metre Convention. He gave a presentation on the activities of the BIPM. The LPEE-LNM gave a presentation that focused on their activities and future plans for successful involvement in the work of the BIPM.

The visit culminated with the signing of the CIPM MRA by Mr Mohammed Berrada, LPEE-LNM Director, and was followed by a tour of the BIPM's physical, chemical metrology and ionizing radiation laboratories with presentations by the scientific staff.

The Kingdom of Morocco had become a Member State on 24 May 2019, raising the number of Member States to 60.

Metrologia: Focus on Metrology in Electricity and Magnetism

Metrologia: Focus on Temperature and Thermal Measurement (TEMPMEKO 2019)

Rapport annuel du BIPM sur les activités du temps (2019)

Début d'une nouvelle phase de dissémination du kilogramme

Journée mondiale de l'accréditation (9 juin 2021) consacrée au soutien à la mise en œuvre des objectifs de développement durable

Rapport annuel du BIPM sur les activités du temps (2020)

Metrologia: Focus on Advances in Metrology in Chemistry and Biology

Metrologia: Focus on Metrology for Dynamic Measurements

Rapport de la 29e réunion du CCT (2020)

Vidéos du symposium du BIPM :
"The International System of Units (SI) in FAIR digital data"

Journée mondiale de la métrologie 2021 : site internet en ligne

On behalf of the World Metrology Day Team, we are pleased to announce that the 2021 World Metrology Day Resource Website is now live. The theme this year is Measurement for Health.

This theme was chosen to create awareness of the important role measurement plays in health, and thus in the wellbeing of every one of us.

World Metrology Day is an annual celebration of the signature of the Metre Convention on 20 May 1875 by representatives of seventeen nations. The Convention set the framework for global collaboration in the science of measurement and in its industrial, commercial and societal applications. The original aim of the Metre Convention - the world-wide uniformity of measurement - remains as important today as it was in 1875.

World Metrology Day 2021: Resource website

Rapport de la 26e réunion du CCQM (2021)

Published on 27th July 2021

Journée mondiale de la métrologie 2020 : site internet en ligne

On behalf of the World Metrology Day Team, we are pleased to announce that the 2020 World Metrology Day Resource Website is now live


The theme for World Metrology Day 2020 is Measurements for global trade. This theme was chosen to create awareness of the important role measurement plays in facilitating fair global trade, ensuring products meet standards and regulations, and satisfying customer quality expectations. Indeed more widely metrology, the science of measurement, plays a central role in scientific discovery and innovation, industrial manufacturing and international trade, in improving the quality of life and in protecting the global environment.


Last year's World Metrology Day was a huge success; we hope to build on that success in 2020.

On the resource website, you may download the Press Release, the Directors' Message and the poster.

Please help us to spread the word about World Metrology Day and let the World Metrology Day Team know by email about the events you are organizing in your country so that we can include them on the website. If you need inspiration, you can see the sort of events organized by other NMIs in previous years on the website.

Report of the 31st meeting of the CCEM (2019)

Charles-Édouard Guillaume

Symposium célébrant le centenaire de l'attribution du prix Nobel de physique à Charles-Édouard Guillaume

On 17 October 2020, the BIPM will celebrate the life and work of Charles-Édouard Guillaume with a symposium, both online and at the BIPM, that will consider his legacy.

The year 2020 marks the centenary of the award of the Nobel Prize in Physics to Charles-Édouard Guillaume (1861-1938). He was born into a watchmaking family in Fleurier (Switzerland), and dedicated more than half a century to metrology through his work at the BIPM. His major study of the properties of nickel-iron alloys spanned more than twenty-five years and not only revolutionized geodesy measurements but also chronometry and precision horology; numerous applications still exist for these alloys. In 1915, he became Director of the BIPM, a position he held until his retirement in 1936.

He was awarded the Nobel Prize in Physics in 1920 "in recognition of the service he has rendered to precision measurements in Physics by his discovery of anomalies in nickel steel alloys".

Details and registration

Atelier du JCTLM les 2 et 3 décembre 2019

The biennial JCTLM Members' and Stakeholders' meeting will be held at the BIPM on 2 and 3 December 2019. A cordial invitation is extended to anyone who has an interest in traceability in laboratory medicine and method standardization. These include laboratory medicine specialists, EQA providers, IVD manufacturers and national metrology institutes.

The meeting takes the form of a workshop that looks at a wide range of global initiatives to reduce between-method variability as a means to support improved clinical outcomes and patient safety. Interaction between the speakers and the audience will be a feature.

The first day of the programme focuses on Challenges and opportunities with lectures on Challenging the status quo and reports on New concepts to improve quality in laboratory medicine; International standards and regulation of IVDs; Meeting the challenge of method harmonization in haematology or biological standardization for infectious diseases.

The theme of the second day of the programme is Getting the right answer with consideration of commutability, harmonization of methods for difficult analytes and looking at international projects for harmonization/standardization.

Participants in the conference will be able to present posters of their work in the area of traceability and method standardization/harmonization. An abstract of the poster should be included with the on-line registration. This is an opportunity for young investigators to discuss their projects with peers and experts in a supportive global community.

Registration to the meeting are open until 31 October 2019.

For any questions please contact the JCTLM Secretariat.

Nouveau secrétaire exécutif du JCRB

On 10 January 2019, Dr Sten Bergstrand, on a two-year secondment from RISE (Sweden), took over as Executive Secretary of the Joint Committee of the Regional Metrology Organizations and the BIPM (JCRB Executive Secretary). Sten takes over from Nikita Zviagin who has returned to VNIIM (St Petersburg, Russian Federation), having completed a two-year secondment at the BIPM.

Sten, the ninth seconded Executive Secretary of the JCRB, has a broad background from geophysical geodesy and length metrology. Until taking up his role at the BIPM he was leading RISE's group in dimension and positioning metrology, with particular interest in GNSS applications and local tie measurements of co-located techniques at space geodetic stations. He has published papers on GNSS monument stability and deformations of geodetic telescopes and was the Swedish representative to EURAMET technical committee for length.

The primary role of the JCRB is to coordinate the activities among the RMOs in establishing confidence for the recognition of calibration and measurement certificates, according to the terms of the CIPM Mutual Recognition Arrangement (CIPM MRA). The JCRB, which is chaired by the Director of the BIPM, is supported by Executive Secretaries seconded from the NMIs from across the globe. This approach strengthens the links between the BIPM and the RMOs, helps transfer knowledge to the RMOs and brings recent "front line" experience to the BIPM. Previous JCRB Executive Secretaries were: Dr Angela Samuel (NMIA, Australia), Dr Ismael Castelazo (CENAM, Mexico), Dr Pedro Espina (NIST, USA), Mr Luis Mussio (LATU, Uruguay), Mr Ömer Altan, (UME, Turkey), Mr Chingis Kuanbayev (KazinMetr, Kazakhstan) and Dr Douglas Olson (NIST, USA).

Année internationale du tableau périodique des éléments en reconnaissance des réalisations de Mendeleev

2019 is the 150th anniversary of the Periodic Table of Chemical Elements and has been proclaimed the "International Year of the Periodic Table (IYPT 2019)" by the United Nations General Assembly and UNESCO.

The periodic classification of the elements was proposed in 1869 by Dmitri Ivanovich Mendeleev, a Russian chemist and former member of the CIPM. He found that by arranging the known elements in order of increasing atomic weight (relative atomic mass), their chemical and other properties regularly repeated. He was therefore able to make a more compact arrangement that was also predictive. By 1871, he produced a more satisfactory version of the table where he left gaps, hoping that they would one day be filled by elements not yet known and predicting with uncanny accuracy the properties of three of those elements, which were very soon discovered: gallium, scandium and germanium. He also predicted a fourth missing element with an atomic weight (relative atomic mass) of about 100. This turned out to be technetium, the lightest element that has no stable isotopes. Mendeleev relied in part on atomic weights accurately measured by Jean-Servais Stas, a Belgian analytical chemist who had also been an important member of the CIPM from its inception in 1875 until his death in 1891, aged 78.

Mendeleev was awarded the Royal Society's award for achievements in chemistry, the Davy Medal, in 1882 (shared with Lothar Meyer, a German chemist). Stas received the same award in 1885.

From 1895 to 1901 Mendeleev was a CIPM member, a role for which he was well qualified following his appointment in 1892 as director of the Main Chamber of Weights and Measures of the Russian Empire (now known as the D.I. Mendeleev Institute for Metrology). During that period he also served as a member of the CIPM Commission on Instruments and Works. He was unanimously granted the status of Honorary member of the CIPM upon his retirement in 1901.

His proposal to complete the redefinition of the unit of volume - the litre by specifying the reference air pressure at which 'one kilogram of pure water at its maximum density (about 4 °C) occupies one litre' was unanimously adopted at the CIPM meeting in 1897 and became incorporated in Resolution 1, 'Declaration concerning the definition of the litre' of the 3rd meeting of the CGPM (1901). (Although his suggestion to specify the air pressure illustrates Mendeleev's life-long attention to detail, the idea of defining the litre to be slightly different from 1000 cm3 did not stand the test of time and was abrogated in 1964, making the litre simply equal to 1000 cm3.)

Mendeleev's 'Examination of Relationship between the Fundamental Measurements of Russia, France and Great Britain based on the data at the beginning of 1897' was published as an Annex to the Minutes of the 20th meeting of the CIPM (1897).

Article de synthèse dans Metrologia sur la révision du SI, aboutissement de trois décennies de progrès réalisés en métrologie

An open-access paper published in Metrologia reviews the changes to the SI that will come into force on 20 May 2019. In particular, the definition of the kilogram will change for the first time since 1889. The definitions of the ampere, the kelvin and the mole will be changd at the same time.

Following three decades of intensive work by the world-wide metrology community, the 26th General Conference on Weights and Measures (CGPM) agreed this major revision of the SI at its meeting in November 2018. The paper includes as an Annex the complete text of Resolution 1 of the 26th CGPM (2018) – On the revision of the International System of Units (the SI).

This Resolution presents the definitions of the base units in a new format that highlights the link between each unit and a defined value of an associated constant. The physical concepts underlying the definitions of the kilogram, the ampere, the kelvin and the mole have been changed. The new definition of the kilogram is of particular importance because it eliminates the last definition referring to an artefact (the international prototype of the kilogram, IPK). In this way, the new definitions use the rules of nature to create the rules of measurement and tie measurements at the atomic and quantum scales to those at the macroscopic level.

The podcast of the historic decision to revise the SI can be viewed on the BIPM's YouTube channel.

BIPM YouTube channel



  • Stock M., Davis R., de Mirandés E., Milton M.J.T., The revision of the SI – the result of three decades of progress in metrology, Metrologia, 2019, 56, 022001

Premier atelier régional sur l'infrastructure de la qualité dans la région du Pacifique

Access to Quality Infrastructure is a major challenge for the island countries of the Pacific. In collaboration with its development partners, the Pacific Islands Forum Secretariat (PIFS) convened the first Regional Quality Infrastructure (QI) Workshop in the Pacific in Nadi (Fiji) on 2-6 September 2019. Andy Henson, Director of the International Liaison and Communication Department at the BIPM was pleased to both present and contribute to the workshop.

The initiative brought together over 80 participants, including government officials and private sector representatives from Forum Island Countries (FIC); international, regional and national organizations playing a leading role in QI; and donor partners.

The workshop prepared and endorsed a Regional Quality Statement summarizing the regional consensus. The workshop will also enable the PIFS to prepare a concept for the second phase of the QI initiative, including a high-level workplan, outlining the implementation of priorities identified by FICs.

This concept note will serve to inform resource mobilization, including but not limited to identification and formulation of a project proposal to be submitted to the Enhanced Integrated Framework (EIF) in the coming months. The EIF is the multilateral partnership dedicated exclusively to assisting least developed countries (LDCs) in their use of trade as an engine for growth, sustainable development and poverty reduction.

The statement, workplan and concept note will also be submitted to the next Pacific Islands Forum Trade Meeting for endorsement.

Atelier CBKT « Important transitions in the CIPM MRA infrastructure » organisé par le BIPM et l'APMP

Over 100 participants from APMP Member NMIs/DIs took part in the joint BIPM-APMP CBKT Workshop entitled "Important transitions in the CIPM MRA infrastructure". The workshop was held on 29-30 November 2019 during the 35th APMP General Assembly in Sydney (Australia). The Workshop was sponsored by the APMP within funds granted as TCI Project TCQS_01_TCQS 2019.

Important transitions

Recommendations from the Working Group on the Implementation and Operation of the CIPM MRA are being implemented. The international standards ISO/IEC 17025 and ISO 17034 have been revised, and NMIs/DIs are improving their systems to complete their transition to these new standards within the three-year period. As an outcome of the CIPM MRA review, the BIPM is renewing the infrastructure of the BIPM key comparison database to transition to the KCDB 2.0, which will include both documentation and web-based tools and systems.

The 2019 BIPM-APMP Workshop was intended to inform participants about these important changes as well as to provide a forum to share experiences.

The Workshop consisted of three sessions:

  • "the CIPM MRA infrastructure from the history to the vast transitions in 2019" with three invited lecturers (Day 1, over 100 participants),
  • "KCDB 2.0 - the new platform for the CIPM MRA" featuring a live demonstration of KCDB 2.0 (Day 2, over 40 participants),
  • "Monitoring the transition of the quality management system to ISO/IEC 17025:2017 and ISO 17034:2016" with fourteen talks from NMIs/DIs presenting their experience in making the transitions (Day 2, around 20 participants).

The workshop provided an effective forum to share knowledge about the KCDB 2.0 and changes to the international standards ISO/IEC 17025 and ISO 17034. An interactive atmosphere was encouraged at the workshop, with many questions from the participants.

Files of the presentations given on Day 1 of the workshop are publicly available on the APMP TCQS website, in the open access area for the TCQS Workshop.

Atelier CBKT « Metrology for Safe Food and Feed - Organic Analysis and Standards » pour les pays de GULFMET

Thirty participants from six members of the GULFMET RMO took part in the three day workshop on "Metrology for Safe Food and Feed - Organic Analysis and Standards", which was organized as part of the BIPM 'Metrology for Safe Food and Feed Programme' Capacity Building and Knowledge Transfer programme. The workshop was sponsored by the GCC Standardization Organization (GSO) and was held from 4-6 November 2019 in Riyadh (Saudi Arabia).

The course addressed general concepts on the role and activities of organizations concerned with the delivery of SI-traceable measurement services to support the analysis of food and animal feed. The workshop included training on the delivery of the infrastructure, capabilities, activities and quality systems necessary to underpin to the provision of reference services in this area. The topics covered were:

  • metrology in chemistry and the role of the BIPM, CCQM, RMOs and NMIs
  • production and use of Certified Reference Materials (CRMs) and primary calibrators to support the reliability and comparability of routine food analysis
  • description of the measurement infrastructure supporting reference measurement services the role of reference measurement services in ensuring laboratory compliance with relevant international accreditation standards (ISO 17025, ISO 17034 and ISO 17043)
  • case studies of the production and application of CRMs, proficiency testing schemes and the provision of reference measurements to underpin analytical services for:
    • nutrient and trace metal content
    • pesticides and drug residues
    • mycotoxin contamination
    • food supplements and adulterants

Workshop activities consisted of a series of lectures and targeted case studies that were intended to maximize knowledge transfer to the participants. A comprehensive overview was provided of best practice and significant challenges for the provision at the national and regional level, and integration at the international level, of a harmonized system of higher-order measurement services and reference materials. This harmonized system will support and sustain routine laboratory analytical services that monitor food safety as well as livestock, crop and plant health.

The lecturers that delivered the workshop were Steven Westwood (BIPM), Ralf Josephs (BIPM), Alpers Isleyen from UME-TUBITAK (Turkey), Byungjoo Kim from KRISS (Republic of Korea) and John Warren from LGC (UK). The participants were able to visit the Saudi Standards, Metrology and Quality Organization (SASO) National Measurement and Calibration Center (NMCC) laboratory located in Riyadh and toured the facilities for measurement services in chemical metrology.

The new instrument for comparing primary standards of pure β-emitting radionuclides

Un nouvel instrument de comparaison des étalons de radionucléides émetteurs de rayonnement β pur

The accurate measurement of radioactivity is essential for applications of ionizing radiation such as medical imaging, cancer therapy and environmental protection. To ensure that such measurements are harmonized world-wide, the BIPM operates a set of very stable and precise instruments to compare national standards of radioactivity. Up till now it has been possible to compare standards of radionuclides that emit gamma rays; setting up an equivalent instrument for radionuclides that only emit beta rays has proved to be a technical challenge. Scientists from the BIPM have worked closely with colleagues from national metrology institutes in Germany, France, Poland, China and the UK to develop a new instrument; the device combines signals from three detectors surrounding a sample of the radioactive standard to determine an accurately reproducible parameter that is proportional to the activity (Bq) of the sample. The method was inspired by one of the techniques used to realize primary standards of radioactivity ('Triple-to-double coincidence counting'). Details have been published in Metrologia.

The new instrument, known as the ESIR, will enable metrology institutes to compare primary standards of pure beta-emitting radionuclides, reducing the need for complex and time-consuming multi-centre comparison exercises.

Contact Romain Coulon for more information.



Lancement par le CCQM-NAWG d'une comparaison sur les procédures d'analyse de l'ARN traçables au SI pour les tests de diagnostic du COVID-19

ICSH, nouveau membre du Comité exécutif du JCTLM

The JCTLM has welcomed the International Council for Standardization in Haematology (ICSH) as a new Executive Committee Member, effective December 2019. The ICSH joins the BIPM, International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and International Laboratory Accreditation Cooperation (ILAC) on the Executive Committee.

The ICSH coordinates Working Groups of experts to examine laboratory methods and instruments for haematological analyses, to deliberate on issues of standardization and to stimulate and coordinate scientific work as necessary towards the development of international standardization materials and guidelines.

This important collaboration brings expertise in clinical laboratory haematology to the JCTLM and provides the opportunity to align the standardization and harmonization of haematology laboratory methods with the reference measurement system of the JCTLM, further enhancing the aim of 'accurate results for patient care'.

Trustworthy data underpin reproducible research

An article entitled "Trustworthy data underpin reproducible research" - coauthored by Martin Milton, Director of the BIPM, and Antonio Possolo, Chief Statistician, NIST - has recently been published in Nature Physics.

The paper presents three case studies from the world of precision measurement, and argues that the work of metrology provides a different way to think about discrepant data without calling it a "reproducibility crisis".

The paper has already been featured in a Nature Physics editorial published on 21 Feburary 2020 under the heading "When it's fine to fail – The history of metrology holds valuable lessons for initiatives to reproduce results." In this the Editor of Nature writes:

  • When results in the science of measurement cannot be reproduced, argue Martin Milton and Antonio Possolo, it's a sign of the scientific method at work – and an opportunity to promote public awareness of the research process.

Read the editorial at:


Nouvel article fournissant des données d'évaluation améliorée de la dose en radiothérapie

A multi-year project involving multiple institutions and coordinated by the International Atomic Energy Agency (IAEA) has culminated in a paper published in the journal Physics in Medicine & Biology. The paper, co-authored by Dr David Burns at the BIPM, provides definitive values for the critical correction factors kQ that enter in the determination of the radiotherapy dose to cancer patients. The new values are derived from a combination of experiment and state-of-the-art Monte Carlo calculations at numerous NMIs and other institutes and have an uncertainty almost a factor of two better than the values currently recommended. They will be incorporated into the IAEA Code of Practice (TRS-398) used by clinicians when evaluating the dose output from their treatment machines. This Code of Practice is currently being revised by a small working group with BIPM participation.

Contact David Burns for more information.


Réunion du Comité scientifique du réseau de laboratoires secondaires d'étalonnage en dosimétrie commun à l'AIEA et à l'OMS

The International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) co-ordinate a network of Secondary Standards Dosimetry Laboratories (SSDLs), designated by IAEA Member States. The IAEA's Dosimetry Laboratory operates as the central laboratory in the SSDL Network and provides calibrations, reference irradiations, comparison programmes and dosimetry audit services for Member States. The aim of the SSDL Network is to improve accuracy in radiation measurements for cancer therapy; for many countries, the IAEA/WHO Network is the route for traceability to the SI for national dosimetry standards.

A Scientific Committee of seven international experts, including Dr David Burns as representative of the BIPM, meets biennially to advise the Directors General of the IAEA and the WHO regarding the programme of the IAEA/WHO SSDL Network and the activities of the Dosimetry and Medical Radiation Physics Section. A meeting of the Scientific Committee was held in March 2020 to discuss recommendations for future work, covering issues such as the use of the new accelerator facility, knowledge-transfer opportunities, the streamlining of calibration services, and database management. The recommendations will be published in the SSDL Newsletter later in 2020.

Time difference between UTC(OP) and UTC(PTB), in nanoseconds, as measured by the usual Two-Way link (green crosses) and improved by the use of a SDR receiver (blue dots), during the period covered by Circular T 386. Red triangles represent the values that have been retained for the calculation of UTC.

Comparaison bidirectionnelle de temps et de fréquences par satellite : première utilisation d'un récepteur SDR pour le calcul de l'UTC

Two-Way Satellite Time and Frequency Transfer, improved by the Software-Defined Radio (SDR) receiver, has been used for Circular T calculation for the first time in March 2020. The comparison between the French and German local realizations of UTC, UTC(OP) and UTC(PTB), was performed using SDR receivers, a method that replaces part of the time-transfer hardware with high-speed digitization and software data processing. This significantly improves the 1-day stability of the time comparison.

Development of this particular SDR receiver has been realized by teams from TL (Telecommunication Laboratories (Chinese Taipei)), LNE-Syrte - Observatoire de Paris (France) and several NMIs within the framework of a Pilot Project launched in 2016 by the CCTF Working Group on TWSTFT. This Working Group had the aim of characterizing the performance of the receiving SDR chain, its long-term stability, the possibility of calibration, and of stable and reliable operation in the long term. The first calibration of such a link has been realized between LNE-Syrte - Observatoire de Paris and the PTB (Germany), paving the way for its inclusion in the Circular T calculation. The BIPM Time Department provided support to the development of this new technique, monitored its results, and assessed its long-term usability for UTC calculation over the last few years.

Extension du Programme CBKT du BIPM afin d'intégrer un service d'apprentissage à distance

The BIPM CBKT Programme has added a "remote-learning" capability, which will provide online assistance to NMI/DI staff from Member States and Associates in their involvement in the CIPM MRA mechanisms.

The remote learning support has two elements aimed to optimize use of the KCDB tools:

We hope these CBKT programme activities will equip those who are involved in developing CMCs on the KCDB platform, as well as TC/WG Chairs and TC/WG Members, with appropriate information.

Informations supplémentaires sur l'utilisation des étalons primaires et secondaires de fréquence pour le calcul de l'UTC

Starting from March 2020, the Time Department is providing additional graphical information concerning the use of Primary and Secondary Frequency Standards (PSFS) in UTC. A graphical representation of all evaluations of PSFS reported since Circular T 190 (October 2003) is available at:


The plot will report the measurements carried out using PSFS and which are used for the steering of TAI. This information, updated every month, will help to evaluate the impact of PSFS in UTC, in view of a possible redefinition of the second.


According to the roadmap towards a redefinition of the SI second (CCTF 2016); a regular contribution to TAI by the new frequency standards is considered one of the criteria for a new definition of the second.

Atelier EURAMET-BIPM sur la KCDB 2.0

The two and half day EURAMET-BIPM Workshop on the KCDB 2.0, dedicated to EURAMET TC Chairs and TC Members, was held at the BIPM from 17-19 February 2020. The Workshop was intended for EURAMET experts who are involved in the CIPM MRA processes. The aim of the workshop was to equip TC Chairs and TC Members (CMC reviewers) with appropriate information to use the KCDB 2.0 effectively.

The KCDB 2.0 is a far more comprehensive system than the one it replaces. The opportunity for the EURAMET experts to gain experience using the simulator was highly appreciated, and they provided the BIPM with useful feedback that will help us optimize the KCDB 2.0 tools going forward.


Andy Henson, Director of the International Liaison and Communication (ILC) Department



The workshop was a follow-up event to the "Optimizing the CIPM MRA - the KCDB 2.0" global course, which was held at the BIPM in November 2019. The content of the workshop was similar to the global course but specifically tailored to the needs of the EURAMET TC community. It was structured to discuss the importance and quality of the data declared into the KCDB; different approaches of EURAMET TCs in intra-regional CMC review practices; CIPM MRA revision outcomes; effective and efficient review practices of the Consultative Committees; and the KCDB tools that have been developed to support these activities.


KCDB 2.0 offline learning tool

Participants worked in groups of five to six on specific topics related to the KCDB 2.0. Practical sessions on the new KCDB 2.0 tools were the most popular part of the workshop; each practical exercise commenced with a demonstration of the relevant KCDB 2.0 tools. The "CMC review simulator" - a dedicated offline KCDB 2.0 learning tool - helped to reinforce the information acquired. The workshop participants simulated the CMC review process using the offline KCDB tool: they prepared and submitted their CMCs as a Writer, acted as Reviewers, submitted comparisons as a Pilot, and finally managed the process as a TC Chair.

The BIPM thanks all participants for their active involvement in the workshop.

Image courtesy of NICT

Première comparaison de fréquences d'horloges optiques à distance par les techniques VLBI et IPPP

Optical clocks have reached a proven accuracy of the order of 10−18 in relative frequency, surpassing the present Cs fountains by two orders of magnitude and driving the Consultative Committee for Time and Frequency (CCTF) to initiate work towards a redefinition of the second. However, comparing these clocks with a similar uncertainty is only possible using optical fibres and is presently limited to a few links at distances not exceeding 1000 km. Radio techniques have world-wide coverage and are currently regularly used in UTC with GNSS-based techniques and two-way time transfer using geostationary satellites, but they have limited accuracy.

Now an international collaboration between the NICT, INRIM, INAF and BIPM has compared the Yb lattice clock at INRIM and the Sr lattice clock at NICT using two new and independent radio techniques. One is Very Long Baseline Interferometry (VLBI), a technique used in astronomy for observing extra-galactic objects, and which has been used for the first time for accurate frequency transfer thanks to the development of mobile antennas and ad hoc hardware and processing facilities. The second technique is Integer ambiguity Precise Point Positioning (IPPP) using GNSS signals, the development of which has been driven by the BIPM over the past few years.

The results obtained with the two techniques agree within the uncertainty of the frequency comparisons, below 3 x 10−16 in relative frequency for each technique. In this case, it is limited by the intermittent operation of the optical clocks and the noise contributed by the "flywheel" clocks used to bridge the gaps. Both VLBI and IPPP are capable of frequency transfer accuracy below 1 x 10−16 when averaging several days and they can be easily combined thanks to IPPP using ubiquitous GNSS receivers that can be operated with the heavier VLBI equipment.

Contact Gérard Petit for more information.

Press release:
Signals from distant stars connect optical atomic clocks across Earth for the first time


Mobile VLBI antenna image courtesy of NICT

Nouvelle série de séminaires virtuels sur la métrologie des rayonnements ionisants

The field of ionizing radiation metrology is constantly evolving, ensuring the effectiveness and safety of new cancer treatments being just one example. A series of international scientific seminars has been launched to share information on progress in the field.

The seminars are co-ordinated by the Consultative Committee for Ionizing Radiation (CCRI) and hosted by the BIPM. The first seminar was held in October 2020 to mark the 60th anniversary of the founding of the BIPM Ionizing Radiation Department. Topics included the CCRI long-term strategy, the work-in-progress on metrology for radiopharmaceutical therapy and recent developments in low electrical current measurement for ionization chambers.

The second seminar on 5 November 2020 was chaired by Dr Annette Röttger from the PTB (Germany). The presentation was a summary of a EURAMET workshop discussing future needs in radiation protection dosimetry. The presentation is available on the BIPM YouTube Channel.

The webinar on 15 December 2020 will cover the international reference system for gamma-ray emitting radionuclides (the SIR). Topics for 2021 include a review of metrology for radiosterilization and a discussion of the new ISO standard for X and gamma reference radiation for calibrating dosemeters and doserate meters (ISO4037). Anyone with an interest in the field is welcome to attend. Links to the webinars are distributed to members of the CCRI, Sections and Working Groups and are also available from the Chairs of the Ionizing Radiation Technical Committees of the Regional Metrology Organizations.

Première CMC soumise, examinée, approuvée et publiée dans la KCDB 2.0

The BIPM KCDB office has published the first CMC that has been submitted, reviewed, approved and published entirely using the recently-launched KCDB 2.0.

A significant milestone was achieved for the BIPM and the KCDB 2.0 on 2 April 2020 with the publication of a CMC for gravimetry from CENAM (Mexico). This represents the first CMC that has been submitted, reviewed and approved entirely using the new KCDB web platform (KCDB 2.0). Whilst the BIPM has published many sets of CMCs in the past weeks (and continues to do so), they were sets that had been reviewed using the old JCRB web facility, and post-processed by the KCDB Office for publication on the new platform. This first publication clearly demonstrates the potential of the new system. The CMC was created and submitted for intra-regional review on 26 February 2020. Having completed the SIM review and being subjected to inter-regional review, it was approved and published just five weeks later on the KCDB on 2 April 2020.

Prix CITAC du meilleur article de 2019

Scientists from National Metrology Institutes and the BIPM working within the CCQM Protein Analysis Working Group (CCQM-PAWG) have been awarded a CITAC Best Paper Award 2019 for their review paper published in the Metrologia Focus Issue on Advances in Metrology in Chemistry and Biology.

The review, entitled Establishment of measurement traceability for peptide and protein quantification through rigorous purity assessment, concentrates on the progress made in establishing methodologies and capabilities to analyse the mass fraction content of pure peptide /protein substances or solutions thereof. Accurately and rigorously characterized pure peptide primary calibrators are essential for the development of Reference Measurement Systems (RMS) for clinical chemistry and laboratory medicine as the basis of a calibration hierarchy for diagnostic tests performed in medical laboratories. Analytes and the related conditions or diseases for which RMSs have been or are being developed include: angiotensins for hypertension; HbA1c, insulin and C-peptide for diabetes; and parathyroid hormone for chronic kidney disease.

The mission of the Cooperation on International Traceability in Analytical Chemistry (CITAC) is to improve traceability of the results of chemical measurement everywhere in the world and to ensure that analytical measurements made in different countries and/or at different times are comparable.


Journée mondiale de la métrologie de 2020 : Les mesures pour le commerce mondial

The theme for World Metrology Day 2020 is Measurements for Global Trade. This theme was chosen to raise awareness of the important role measurement plays in facilitating fair global trade - ensuring products meet standards and regulations, and satisfying customer quality expectations. At the time of writing a total of 35 versions of the World Metrology Day 2020 poster have been produced, primarily by NMIs around the world. In addition, 14 events have been organized, many of them virtual. Additional posters and events will be added as the information arrives.

The Directors of the International Bureau of Legal Metrology (BIML) and the International Bureau of Weights and Measures (BIPM), have prepared a joint statement to promote World Metrology Day. This is available from the World Metrology Day website, which also includes four video messages for 2020 presented by the Presidents of the CIPM and the CIML and a joint message presented by the Director of the BIPM, in collaboration with the Director of the BIML. In addition, Dr Milton presents a special video message for World Metrology Day 2020 in the context of the COVID-19 pandemic, particularly how national metrology laboratories and quality infrastructure systems around the world have addressed the fast-moving challenges that have arisen as a result of the crisis.



From NIAID-RML [CC BY 2.0]

Garantir la fiabilité des mesures dans le contexte de la pandémie de COVID-19 : webinaire du CCQM et numéro spécial de la Newsletter du JCTLM (juillet 2020)

A special edition of the JCTLM Newsletter focuses on the reliability of measurements in COVID-19 diagnostics:

The Newsletter summarizes articles submitted by JCTLM Members and Stakeholders presenting their work on the reliability of COVID-19 diagnostic measurements - including reference materials, reference measurement methods, interlaboratory comparisons and relevant research, publications and seminars.


The Newsletter also includes a report on a special CCQM webinar, held on 7 July 2020. Presentations during the webinar included:

  • Review of diagnostic modalities involved in the response to the COVID-19 pandemic - Prof. Jacob Moran-Gilad
  • International proficiency testing scheme results with molecular diagnostics for SARS-CoV-2 - Prof. Heinz Zeichhardt
  • SARS-CoV-2 antibody testing and what we can learn from interlaboratory studies - Prof. Michael Neumaier
  • The development and assessment of COVID-19 serological platforms - Dr Michael A. Drebot

Webinar programme: Ensuring the reliability of measurements in response to the COVID-19 pandemic

Image: from NIAID-RML [CC BY 2.0]

Webinaire de l'OCDE : « International Organisations and their Members Facing the Global Crisis Together »

Dr Martin Milton, Director of the BIPM, together with heads of other international organizations (IOs), participated as a panelist in the OECD High-Level Webinar: "International Organisations and their Members Facing the Global Crisis Together". The virtual meeting was held on 3 September 2020 as part of the 7th Annual IO Meeting within the context of the IO Partnership.

Following the High-Level Webinar, a second Webinar: "The IO Partnership in Action: Towards a Compendium of IO Practices and Beyond - Self-reflection, Peer-Learning and Adapting to a Changing World" took place in which the BIPM reported back from the 'WG5 on Coordination among IOs' breakout session, held on 31 August 2020. The BIPM shares the role of focal point of WG5 to better tailor the specific needs of IOs and address more in-depth coordination issues.

The IO Partnership is currently working on a Compendium of International Organisations' Practices for Effective International Rulemaking. The Compendium will use examples from the BIPM and from many other IOs to highlight how IOs work better together and how they can learn from each other about best practices as they go forward.

The OECD established the Partnership of international organisations for effective international rulemaking (IO Partnership) as a voluntary platform of IOs, academics and OECD Regulatory Policy Committee delegates, to exchange good practices and promote greater quality, effectiveness, and impact in international rulemaking.

For more information on the 7th Annual Meeting of International Organisations please see


Le Programme CBKT du BIPM devient virtuel

The BIPM CBKT Programme launched its "Remote learning support" initiative in May 2020 with the delivery of its first online short course for RMOs (COOMET) and its first online technical exchange for CMC writers (Q/A sessions).

The KCDB 2.0 - an online short course

This newly developed online course attracted more than 100 participants from COOMET who are directly involved in the operation of the CMC review process and who pilot comparisons. The short course was split into three one-day sessions from 25 to 27 May, with each session lasting around three hours. The modules addressed:

  • User accounts
  • Creation of CMCs
  • CMC review processes
  • Comparisons
  • KCDB search facilities
  • Statistics.

Each module was followed by a series of multiple choice questions to the participants to establish immediately how well the content had been understood. This allowed the KCDB experts to continue by focusing on the aspects participants had found most challenging.


On behalf of COOMET President, COOMET expresses its gratitude to the BIPM for the provided opportunity of participation for a wide range of experts from COOMET NMIs/DIs in the short online course on the KCDB 2.0 issues and to all speakers for their interesting reports. Thank you very much!

Nadezhda Liakhova, Head of the COOMET Secretariat

See also:

COOMET news about this event


Technical exchanges

As part of a brand-new initiative, the BIPM is delivering capacity building and knowledge transfer directly to those NMIs/DIs staff around the world who initiate CMCs.

The first of a series of one-hour technical exchanges on the KCDB 2.0 were focused on CMC writers in General physics and took place on 9 June 2020. In order to cover all time zones and ensure the participation of CMC writers around the world, the sessions were organized at 09:00 and again at 16:00 CET. This flexible approach to timing allowed the participation of 129 CMC writers, representing almost all regions. The technical sessions are based on a 'question and answer' format. All registered participants submitted their questions in advance to allow the KCDB experts to prepare and deliver tailored demonstrations using the KCDB CBKT training platform.

The "Remote learning support" initiative was launched to assist NMI/DI staff from Member States and Associates with their involvement in the CIPM MRA mechanisms. The BIPM is confident that these initiatives will equip those who are initiating CMCs, and those who operate the CMC review processes, thus increasing the effectiveness of the KCDB database as a reliable source for information on metrological traceability.

The BIPM is highly satisfied with the initial outcomes of the remote learning support. The feedback has been very positive, with the RMOs and participants in both activities clearly stating that they have received valuable and practical information that can be implemented directly in their work.

Chingis Kuanbayev, BIPM International Liaison and Communication Department

Prix Enrico Fermi décerné à Patrizia Tavella par la Société italienne de physique

Dr Patrizia Tavella, Director of the BIPM Time Department, has been awarded the Enrico Fermi Prize by the Italian Physical Society. The prize was awarded jointly to Patrizia and Dr Giovanni Mana (INRIM), Deputy Editor of Metrologia. The citation reads: "for their original and important contributions to the measurement of time and to the definition of mass".

The Prize was established in 2001 to mark the centenary of the birth of Enrico Fermi and is awarded by the Italian Physical Society each year to those who have made important contributions to physics. It was presented during the Opening Ceremony of the 106th National Congress of the Italian Physical Society which was held on-line.

Many congratulations to Patrizia and to Giovanni. The award of the prize to scientists working in metrology underlines the importance of this field to the world of science.

Vers une surveillance plus précise de l'ozone troposphérique

Participants at the BIPM virtual workshop on 'Accurate Monitoring of Surface Ozone' from air quality monitoring networks, environment agencies, instrument manufacturers and metrology institutes, agreed to work together to develop an implementation plan to enable more accurate surface ozone measurements world-wide. The workshop was held from 5 to 9 October 2020. Over 100 participants connected online to provide input into the recommendation of the virtual workshop, which was organized by the CCQM Working Group on Gas Analysis (CCQM-GAWG).

The reference method for ground-level ozone measurements is based on UV photometry, with NIST Standard Reference Photometers (SRP) acting as primary standards for numerous national and international ozone-monitoring networks. Measurements of ozone amount fractions in ambient air are ultimately anchored to the value and uncertainty of the ozone absorption cross-section at the wavelength 253.65 nm. A review of all measurements of the absorption was carried out and published in 2019, providing a consensus value 1.23 % lower, and an uncertainty six times smaller, than the historically used value. A globally coordinated effort will now be required to implement the 2019 value in ozone measurement systems around the world in an orderly way.

The workshop gathered representatives of reference laboratories, monitoring networks, regulators and ozone analyzer manufacturers to develop a plan and timetable to allow a globally coordinated and universal implementation of the ozone absorption cross-section value published in 2019.

Presentations given during the workshop are available on the workshop webpage, including the results of discussions held within the four Task Groups and reported during the last day. A more detailed report of the workshop will be published soon.

BIPM virtual workshop on 'Accurate Monitoring of Surface Ozone'


The workshop noted the importance of accurate measurements of ozone and their uniformity, independently of the region of the atmosphere or with measurement platform or technique with which they were made. It recommended that a Task Group be created to manage the change process of the ozone cross section value, and this be established by the CCQM Working Group on Gas Analysis (CCQM-GAWG), with membership to include all stakeholder communities. The recommendations of the workshop will be published before the end of 2020, including a communication on the intention to implement a change in the globally used value of the ozone cross section and its uncertainty. The workshop estimated that the change process may take between three to five years to be completed, noting that documentary standards and air quality regulations would require updating as part of the change process. A detailed plan and roadmap of the change process will be developed by the task group.


CCQM-GAWG Statement

Following stakeholder consultation during the Workshop, the CCQM Gas Analysis Working Group is issuing a statement on its intention to change the Ozone Cross-Section Value used for Surface Ozone Standards and Measurement.

Statement: Intention to change the Ozone Cross-Section Value for Surface Ozone Measurement

Rapport de la 12e réunion du CCAUV (2019)

Publié le 28 février 2019.

Rapport de la 24e réunion du CCU (2019)

Publié le 1<sup>er</sup> décembre 2020.

CDC/ Alissa Eckert, MSMI; Dan Higgins, MAMS

Haute exactitude d'un système de mesure de référence pour les tests SARS-CoV-2 démontrée par les laboratoires nationaux

Twenty-one National Metrology Institutes and expert laboratories from sixteen countries have demonstrated that highly accurate measurements of the amount of the SARS-CoV-2 viral RNA can be achieved worldwide using reverse transcription-digital PCR (RT-dPCR). The ability to accurately measure the amount of the viral cause of COVID-19 with global equivalence will considerably improve testing confidence and support countries in effectively tackling the pandemic.

The comparison study (CCQM-P199.b) organized by the CCQM Working Group on Nucleic Acid Analysis (CCQM-NAWG), and coordinated by the National Measurement Laboratory at LGC (UK), NIM (China), NIBSC (UK) and NIST (US), required quantification of the same viral genetic sequences targeted by many of the diagnostic tests. The RT-dPCR results were found to agree very well with each other and different SI-traceable non-molecular orthogonal methods; most values were within +/-40% of mean. The reproducibility of the method is unprecedented for absolute molecular measurements, where orders of magnitude of spread in reported copy numbers can be found using conventional molecular diagnostic methods. This work, made possible by over a decade of CCQM led collaborative efforts within the bio-metrology community, represents the most comprehensive example of highly reproducible and sensitive measurement of RNA and opens the possibility for SI-traceable quantification of viral genes. The methods and results are already being used by National Metrology Institutes to value assign reference materials that underpin the quality of SARS-CoV-2 diagnostic tests. The comparison was conducted under an accelerated timeline, with the worldwide comparison completed in under six months, and the final report expected in early 2021.

In the longer term, these capabilities have far wider implications as they can provide a global foundation for ensuring the accuracy of associated molecular methods whether applied to COVID-19, as preparation for any future global pandemic or for wider diagnostic uses such as in testing for antibiotic resistance or cancer.

Results from part of the study demonstrating that laboratories performing molecular RT-dPCR methods are able to perform with good agreement with each other and the SI-traceable orthogonal methods (isotope-dilution mass spectrometry and single molecule flow cytometry), the latter providing the basis for the RT-dPCR method's claimed accuracy. The RT-dPCR results were compared with orthogonal methods using different concentrations of the same RNA material. The different concentrations were prepared using gravimetric dilution. Diamonds show individual laboratories' results with solid black line (mean) and dotted green lines +/-40% of mean value.

Rapport de la 17e réunion du CCM (2019)

Publié le 14 octobre 2019.

Rapport de la 25e réunion du CCQM (2019)

Publié le 22 juillet 2019.

Rapport de la 27e réunion du CCRI (2019)

Publié le 17 octobre 2019.

Comparaison internationale démontrant l'exactitude de l'échelle de mesure mondiale du CO2 dans l'air

The results of the CCQM comparisons on CO2 in air standards (CCQM-K120 and CCQM-P188) were presented at the 20th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases, and Related Measurement Techniques (GGMT-2019), which was held in Jeju (Republic of Korea) from 2-5 September 2019. This coincided with the presentation of an updated carbon dioxide scale (WMO-CO2-X2019), the primary reference for the WMO-GAW monitoring network on which all global background observations of carbon dioxide are based.

The scale will be used by the WMO Global Atmosphere Watch programme in its global monitoring network for tracking trends in the background carbon dioxide amount fraction in the atmosphere. The accuracy of the scale was demonstrated in the key comparison (CCQM-K120), organized by the CCQM Gas Analysis Working Group with comparative measurements performed at the BIPM. The comparison was a substantial undertaking involving the analysis of the composition of 46 gas reference materials from 13 National Metrology Institutes (NMIs) and The National Oceanic and Atmospheric Administration (NOAA), the institute designated by the WMO.

Progress in reducing uncertainties in SI traceable standards has led to a key comparison reference value for carbon dioxide in air concentrations with state-of-the-art uncertainties of parts in 104. This has enabled benchmarking of international comparability and provided support for an update to the global scale. Standards developed by NMIs with gravimetric preparation were a major contributor in delivering reference values for CO2 in air with the smallest uncertainties achieved to date. The comparison also required methods to accurately calibrate optically-based instruments for CO2 isotope ratio (δ13C and δ18O) measurements to be developed at the BIPM as well as a manometric facility for future ongoing comparisons of CO2 in air standards, the performance of which was demonstrated in the CCQM-P188 study.

The developments to the global scale recognize the substantial collaborative progress made between the metrology and atmospheric monitoring communities since the WMO signed the CIPM Mutual Recognition Arrangement (CIPM MRA) in 2010.

Nouveaux présidents du CCAUV et du CCRI

Dr Héctor Laiz, Director of Metrology, Quality and Environment at the Instituto Nacional de Tecnología Industrial (INTI), Argentina, was appointed as the President of the Consultative Committee for Acoustics, Ultrasound and Vibration (CCAUV). Dr Laiz succeeds Dr Takashi Usuda, who had been CCAUV President since 2014.

Dr Martyn Sené, Deputy CEO of the National Physical Laboratory (NPL), UK, was appointed as President of the Consultative Committee for Ionizing Radiation (CCRI). Dr Sené succeeds Dr Wynand Louw, who has stepped down from the role that he had held since 2014.

Both Dr Laiz and Dr Sené have been members of the CIPM since 2016.

Atelier de 2019 du CCRI Workshop (2019) sur la stratégie pour 2020-2025

Publié le 28 février 2019.

Patrizia Tavella reçoit le prix 2019 de l'European Frequency and Time Forum (EFTF)

Dr Patrizia Tavella, Director of the BIPM Time Department, has been awarded the European Frequency and Time Award 2019 "for her engagement and key achievements in time and frequency dissemination at both scientific and educational levels." The European Frequency and Time Award recognizes outstanding contributions in all fields covered by the EFTF.

Renforcer la chaîne dosimétrique internationale

The IAEA organizes a major international symposium on standards, applications and quality assurance in medical radiation dosimetry (IDOS) about once every 10 years. The aim of the symposium is to disseminate advances in radiation dosimetry for medicine and radiation protection, summarizing the trends in the field and identifying areas for improvement.

The 2019 conference was held in Vienna (Austria) on 18-21 June, and was attended by more than 500 clinicians, medical physicists and metrologists from 105 countries. In addition to covering developments in dosimetry for external beam radiotherapy, radiography and radiation protection, the challenge of accurate dosimetry for molecular radiotherapy was discussed.

The BIPM was actively involved in the symposium, contributing to the organizing committee and presenting an overview of traceability in radiation dosimetry.

Le CIPM nomme le nouveau président du CCQM et celui du CCTF

The CIPM appointed two new Consultative Committee (CC) Presidents at Session I of its 108th meeting (March 2019).

Dr Sang-Ryoul Park, President of the Korea Research Institute of Standards and Science (KRISS), Republic of Korea, was appointed as President of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) for a four-year term. Dr Park succeeds Dr Willie May, who has stepped down from the role that he had held since 2011.

Dr Noël Dimarcq, Deputy Director of the Observatoire de la Côte d'Azur, France, was appointed as the President of the Consultative Committee for Time and Frequency (CCTF) for a four-year term. Dr Dimarcq succeeds Mr Luc Érard, who had been CCTF President since 2007.

Both Dr Park and Dr Dimarcq were elected to the CIPM at the 26th meeting of the CGPM in November 2018. They took their seats at the CIPM for the first time in March 2019.

Élection du bureau du CIPM

During the first session of its 108th meeting (20-21 March 2019) the CIPM elected the following to form the bureau of the Committee:

  • President - Dr W. Louw (South Africa)
  • Secretary - Dr T. Usuda (Japan)
  • Vice-Presidents - Prof. J. Ullrich (Germany) and Dr J. Olthoff (United States of America)

The 108th meeting was the first to be held following the 26th meeting of the CGPM (November 2018), at which all 18 CIPM members were elected. Six of those elected participated in the CIPM for the first time:

  • Dr D. del Campo Maldonado (Spain)
  • Dr N. Dimarcq (France)
  • Prof. P. Neyezhmakov (Ukraine)
  • Dr J. Olthoff (United States of America)
  • Dr S.-R. Park (Republic of Korea)
  • Dr A. Steele (Canada).

Le Système international d'unités - des mesures fondamentalement meilleures

The 20th May 2019 marks a particularly special celebration of World Metrology Day because it is the day chosen for the implementation of the changes agreed to the definitions of the SI base units. These landmark changes were decided at the 26th meeting of the General Conference on Weights and Measures (CGPM), which took place in Versailles in November 2018.

From 20 May 2019 the International System of Units (SI) embraces one of the most significant changes since its establishment - the definitions of four units (the kilogram, the ampere, the kelvin and the mole) are also linked to physical constants, which ensure their stability and universality. More information on the impact the redefinition has on the realization of the units is available on the BIPM website.

The world-wide promotional activities surrounding the meeting of the CGPM last November were very successful; we hope that the efforts to generate awareness about the implementation of the decisions will be similarly effective. Many examples of initiatives under way around the world are available from the World Metrology Day resource website (

Whilst the motivation for the changes to the definitions has been to provide new opportunities to increase access to accurate measurements there are some small changes that come into effect today that will concern laboratories working at the highest levels in the mass and electricity communities. Information about these changes is available on the BIPM website.

We wish success to all activities around the world on World Metrology Day that are raising awareness of how the SI is "Fundamentally Better".

État de l'art en métrologie des radionucléides

The biennial international conference on radionuclide metrology (ICRM) was held on 27-31 May 2019 in Salamanca (Spain). The conference covered developments in primary standards and novel technologies for measuring radioactivity (for example, the use of unmanned airborne spectrometers for environmental measurements).

Staff from the BIPM contributed presentations on the international reference system for pure beta emitting radionuclides (the ESIR) and the first measurement of 11C in the transportable instrument for short-lived gamma emitters (SIRTI).

The Chair of CCRI Section II gave a presentation on the long-term strategy for radionuclide metrology. The proceedings will be published in a special issue of Applied Radiation and Isotopes.

École d'été de Varenne de 2019

The BIPM and the Italian Physical Society ran the highly successful joint Metrology School "New frontiers for metrology: from biology and chemistry to quantum and data science" at the International School of Physics Enrico Fermi in Varenna (Italy), from 4-12 July 2019. The school was jointly organized with INRIM and this was the seventh summer school in metrology held since 1976. A total of 81 applications were received from 25 different countries and 56 students and observers were selected to participate.

Sponsorship by METAS, the Swiss NMI, under the auspices of the BIPM CBKT programme, provided opportunities for a number of participants to attend from NMIs/DIs of Member States or Associates that have emerging metrology systems. These award winners were able to combine their attendance at the Metrology School with a short (two- to six week) placement at METAS to pursue a specific metrology topic of interest. The grant was aimed at young metrologists with strong scientific ability and potential and who are expected to be the 'high flyers' of tomorrow.

The Metrology School had a world-class line-up of 22 lecturers including five from the BIPM and the Nobel laureate Prof. William Phillips. There were numerous opportunities for the students and lecturers to network informally at events outside the lectures, providing opportunities to form useful contacts for the future.

The Varenna Metrology School consisted of modules on physical and chemical metrology as well as fundamental issues common to all parts of metrrology.

Mesures plus exactes du CO2 à l'aide de l'analyse isotopique

A recent publication from the BIPM demonstrates how the isotopic composition of CO2 in air standards can be used to correct precise spectroscopic measurements to achieve the accurate assignment of concentration. The method was applied to the international comparison of 46 standards from sixteen NMIs and designated institutes, demonstrating reference values with standard uncertainties of 1 part in 104, providing the most accurate comparison of greenhouse gas standards for background and urban concentrations to date.

The paper [1] has confirmed that spectroscopic (FTIR, but also applicable to laser-based systems) based measurements of CO2 mole fraction can be employed to achieve standard uncertainties reaching 0.05 µmol mol−1, even if sample and calibration gases isotopic ratios differ. The measurement of, and correction for, isotope ratios of CO2, for amount of substance fraction comparisons was recently demonstrated in the CCQM-K120 [2] (2019) and CCQM-P188 [3] (2019) comparisons of CO2 in air standards at nominally (380, 480 and 800) µmol/mol. These compared 46 standards from National Metrology Institutes, the WMO's Central Calibration Laboratory and the Integrated Carbon Observation System‑Central Analytical Laboratories (ICOS-CAL) laboratory, as well as the reference systems at the BIPM. The comparisons, carried out with comparative measurements at the BIPM, including bias corrections from differences in isotope ratios in standards, allowed reference values with standard uncertainties of 0.05 µmol/mol to be determined: a four-fold reduction compared to comparisons performed 10 years previously. The pilot study comparison also demonstrated the performance of the manometric reference facility for CO2 in air standards, which is being developed at the BIPM, as a unique common reference to be used in the on-demand comparison (BIPM.QM-K2) of CO2 in air standards across the range (380-800) µmol/mol.

The comparisons on CO2, form part of series of comparisons on greenhouse gas standards, also including methane and nitrous oxide, coordinated by the BIPM on behalf of the CCQM Working Group on Gas Analysis and described in two recent publications on 'SI traceability and scales for underpinning atmospheric monitoring of greenhouse gases' [4] and 'Advances in reference materials and measurement techniques for greenhouse gas atmospheric observations' [5]. Future comparisons are planned for 2019 (N2O), 2022 (CO2) and 2023 (CH4). A comparison of isotope ratio measurements in CO2 gas (CCQM-P204) is being coordinated by the BIPM in collaboration with the IAEA, with measurements planned in 2020.

  1. Flores E., Viallon J., Moussay P., Idrees F. and Wielgosz R. I. An FTIR method for accurate CO2 mole fraction measurements with correction for differences in isotopic composition of gases, Metrologia, 2019, 56(4), 044005.
  2. Flores E. et al. CCQM-K120 (Carbon dioxide at background and urban level), Metrologia, 2019, 56, Tech. Suppl., 08001.
  3. Flores E., Viallon J., Choteau T., Moussay P., Idrees F., Wielgosz R.I., Meyer C., Rzesanke D. Report of the pilot study CCQM-P188: Carbon dioxide in air (380 to 800) µmol/mol., Metrologia, 2019, 56, Tech. Suppl, 08012.
  4. Brewer P.J., Brown R.J.C., Tarasova O.A., Hall B., Rhoderick G.C., Wielgosz R.I. SI traceability and scales for underpinning atmospheric monitoring of greenhouse gases, Metrologia, 2018, 55(5), S174-S181.
  5. Brewer P. J., Flores E., Viallon J. et al. Advances in reference materials and measurement techniques for greenhouse gas atmospheric observations, Metrologia, 2019, 56(3), 034006.

Initiative commune au BIPM et à TÜBİTAK UME couronnée de succès et étendue à 2020 et 2021

The joint BIPM–TÜBİTAK UME initiative "TÜBİTAK UME project placements" has proven a great success. The BIPM collaborated with TÜBİTAK UME, the National Metrology Institute (NMI) of Turkey, to support young metrologists from 14 countries to gain in-depth knowledge and experience on a subject of scientific interest.

Over two cycles, organized in 2018 and 2019, the BIPM and TÜBİTAK UME initiative sponsored 20 participants from AFRIMETS, APMP, COOMET and GULFMET. All participants were from NMIs that have recently become a signatory to the CIPM MRA, or were inexperienced in the CIPM MRA processes. The placements, of between 1 and 3 months, hosted in the TÜBİTAK UME laboratories, allowed participants to focus on specific metrological projects, to learn the theory and to test it in practical situations in order to maximize the transfer of knowledge. In addition, participants were able to gain a better understanding of the international aspects of metrology during the seminars organized under the joint initiative and delivered by BIPM and TÜBİTAK UME staff.

Brief reports from the participants are available from the BIPM's CBKT pages.

The number of applications received for both cycles demonstrates the huge interest and demand for this joint initiative. The first cycle received 58 applications from 23 countries and the second 48 applications from 18 countries, competing for the 10 slots that were available in each cycle.

As a consequence of the success of this training initiative and the significant ongoing demand for capacity building and knowledge transfer training, we invite other NMIs to join this initiative. These actions reflect the encouragement to carry out knowledge transfer and mentoring activities that were underlined in the Recommendations from the Working Group on the Implementation and Operation of the CIPM MRA.

The BIPM acknowledges with thanks the major contributions of TÜBİTAK UME to the BIPM's CBKT activities.


Andy Henson and I were delighted to meet the participants at our joint capacity building initiative with TÜBİTAK UME.

The seminars provided a great opportunity to mingle with the new generation of metrologists. Their enthusiasm was infectious, and our discussions were continued in a very friendly atmosphere over lunch, during coffee breaks and free time. They were open and ready to share their experiences and challenges... and really keen to learn and gain experience.

I wish all the participants the best of luck in implementing the outcomes of their projects, and every success in their next steps in the world of measurement uncertainties and metrological traceability.

Huge thanks to TÜBİTAK UME colleagues for making the initiative a success!

Chingis Kuanbayev, BIPM

Barry Inglis membre honoraire du CIPM

At Session II of its 108th meeting (October 2019), the CIPM decided that it would bestow honorary membership on Dr Barry Inglis in recognition of his accomplishments as the President of the CIPM. These accomplishments had an impact across the organization.

Dr Inglis was a member of the CIPM from 2000 to 2019 and served as President of the CIPM for eight years from 2011 to 2019. In addition, Dr Inglis had been President of the Consultative Committee for Electricity and Magnetism (CCEM) from 2003 to 2015 and Vice-President of the CIPM from 2002 to 2011.

During his time as President of the CIPM, Dr Inglis led the organization through two meetings of the General Conference on Weights and Measures (CGPM). He led the CIPM through the governance review and subsequent launch of the reform of its processes. His work in coordinating the work of the CIPM with its Consultative Committees and the global NMI community led to the successful adoption of revised definitions for the SI units in 2018. The CIPM acknowledged that Dr Inglis always took a strategic and long-term view of the impact of the CIPM on world metrology.

Mise en ligne du nouveau site internet de la KCDB (KCDB 2.0)

The new KCDB website (KCDB 2.0) went live on 29 October 2019 with extended search facilities. It is now possible to search on CMCs and comparisons using a free-keyword search - quick search - or by using a predefined menu - advanced search. You may also filter on CMC approval dates, combine an advanced search with free key words, filter CMC measurand values and uncertainties numerically, sort results and export search results to a spreadsheet.

A user platform with restricted access for creating and reviewing CMCs, and registering comparisons, will open in November 2019.

A new statistical tool is planned for the beginning of 2020.

Protocole d'accord avec l'International Union of Pure and Applied Chemistry (IUPAC)

The BIPM and IUPAC have formalized their long-standing cooperation through the signature on 17 October 2019 of a Memorandum of Understanding.

The BIPM-IUPAC Memorandum of Understanding was signed by Dr Wynand Louw, President of the CIPM, and by Christopher M.A. Brett, Vice President of IUPAC, on behalf of the IUPAC President, Qifeng Zhou.

The BIPM has for many years been represented on the IUPAC Interdivisional Committee on Terminology, Nomenclature and Symbols (ICTNS), and IUPAC participates in the CCQM, the CCU and the JCGM.

Formation destinée aux experts du CIPM MRA afin d'optimiser leur utilisation de la KCDB 2.0

The one-week course entitled "Optimizing the CIPM MRA - the KCDB 2.0", organized by the BIPM and sponsored by NIST, was held from 4-8 November 2019 at the BIPM and was attended by 27 CIPM MRA experts. The aim of the course was to equip those who operate the CIPM MRA CMC review processes with appropriate information, and to ensure that they will not learn the new KCDB 2.0 elements by 'trial and error'.

The BIPM, in response to the recommendations from the CIPM ad hoc Working Group on Implementing the Recommendations from the Review of the CIPM MRA, developed and launched a new system - the KCDB 2.0 in October 2019. It integrates the whole CMC review process into a single platform - from development of CMCs to publication in the KCDB. The manual transfer of the CMCs' Excel files for review and publication is no longer required in the new system. The system also encourages the consistency of data from the beginning. In the original KCDB, the first of the two-tier CMC review process was organized remotely and was coordinated manually by the RMO TC Chairs at the regional level, and the inter-RMO review process was organized through the JCRB database. The CMCs themselves were developed using the Excel templates by NMIs/DIs, and communicated manually to the review processes.

Optimizing necessary competences

Operation of the CMC review process is complex and requires careful examination of NMI/DI capabilities submitted for publication in the KCDB. It was considered that the KCDB 2.0 could present a challenge if TC/WG Chairs and TC/WG Members were not familiar with the new menu of tools in the database; the course was designed to optimize their knowledge of these tools. Each practical exercise commenced with a demonstration of the relevant tools available in the KCDB 2.0. The "CMC review simulator" - a dedicated offline KCDB 2.0 learning tool - helped to reinforce the information acquired. The course participants wrote and submitted their CMCs as a Writer, acted as Reviewers, submitted comparisons as a Pilot, and finally managed the process as a TC Chair. The hope is that the participants will share experiences within their TC/WG community and explain the operation of the KCDB 2.0 to the NMIs.

Refreshing the knowledge about the CIPM MRA and sharing best operation practices

The course content additionally provided information to refresh participants' knowledge about the CIPM MRA requirements and its review outcomes. Each stage of the process during the practical exercises was supported with lectures describing the requirements.

The course content also addressed the different approaches taken by the Consultative Committees and RMOs for CMC review and comparisons. Their guidelines and templates ensure a reduced workload and harmonization of different RMO practices within their metrology area. With respect to this, Elsa Batista, a participant from EURAMET TC F CMC Coordinator group, stated in her feedback that:

"This was a very good opportunity to be informed about the organization of each CC and learn from other fields of activities. It was verified that there are guides and templates available on several committees webpages that can be adopted in my one area of work, Flow and Volume. I would suggest that the Chairs of each TC can meet more often in order to exchange good practices for a decreased workload of the MRA."

Support of NIST

The BIPM acknowledges the US Government Grant from the National Institute of Standards and Technology (NIST) which enabled the BIPM to run this course.


This CBKT course on the new KCDB 2.0 and on efficient implementation of the CIPM MRA has been a great success. I highly appreciated that straight from the very beginning of this course, there were extensive and lively discussions of the participants and the lecturers on the subjects presented. The course provided ample opportunities for the participants (many of them TC chairs) to learn how to more effectively implement the CIPM MRA and to exchange best practices between RMOs and different technical disciplines. This CBKT course has made a highly valuable contribution into further efficient implementation of the CIPM MRA. I expect that the extensive training in the use of the just-launched KCDB 2.0 will be of great value in the successful introduction of the KCDB 2.0 in the metrology community. I thank BIPM for doing such a great job in the organization of this CBKT course, and I thank NIST for their financial support to make this CBKT course happen.

Dr Gert Rietveld, CCEM President and CIPM member


The brainstorming activity at the end of the course was the best strategy to consolidate the knowledge acquired in a week, taking as an example the case studies and best practices shared by the participating colleagues. The list of the "hints of use of the KCDB 2.0" constitutes an excellent introduction manual to familiarize new users of the KCDB 2.0 and also to clarify doubts of the constant users.


Liz Catherine Hernández Forero, INM, Colombia
The BIPM frequency comb installed in the laboratory at INTI

Peigne de fréquence du BIPM à l'INTI

Before retiring in March 2018, Dr Lennart Robertsson dismantled the former BIPM Length section's laser laboratory. A number of pieces of equipment were identified as being worth offering to NMIs for use in their work programmes. In particular, there were two frequency combs, which had been built by the BIPM and which are used in comparing microwave to optical frequency radiations. Information about the frequency combs was circulated among the NMIs and INTI (Argentina) offered to acquire one of the combs.

Karina Bastida from INTI visited the BIPM in November 2018, where she worked for one week alongside BIPM colleagues and Lennart Robertsson, who returned to the BIPM to explain the operation of the different components. Karina, with the support of Laurent Tisserand and the BIPM workshop, prepared six large shipping containers ready for transporting the comb. In addition she prepared a list of documents to obtain customs clearance with the support of the BIPM Director's Office.

It took more than nine month to receive the custom clearance, and on 16 October 2019 the comb left the BIPM. It arrived at INTI a few days later and Karina and her colleagues have successfully installed the equipment. INTI is pleased with the new capability in its length laboratory. Dr Héctor Laiz, CIPM member and Director of Metrology at INTI, provided considerable support towards this transfer to improve INTI's capabilities in this area.

École d'été de Varenne de 2019 et projet METAS

In July 2019 the BIPM, in collaboration with the Italian Physical Society organized the Metrology Summer School "New frontiers for metrology: from biology and chemistry to quantum and data science" in Varenna (Italy).

The Summer School was presented as a series of modules, with a 3-day core module on the "Fundamental Metrology" and a choice of two 3-day optional modules: "Physical metrology" and "Quality of life".

METAS, the Swiss NMI, supported the participation of three young metrologists with strong scientific ability/potential, who are expected to be the 'high flyers' of tomorrow under the auspices of the BIPM Capacity Building and Knowledge Transfer Programme. The three award winners Rafidah Rosli from NMIM (Malaysia), Julián Gigena from INTI (Argentina) and Jorge Pereira from IPQ (Portugal) were able to combine their attendance at the Metrology School with a short placement at METAS. During their internship of two-to-four weeks, they received dedicated training and pursued a specific metrology topic of interest.

Brief reports from the participants are available from the METAS news.

Progrès considérables en 2019 de la balance de Kibble du BIPM concernant la réalisation de la nouvelle définition du kilogramme

The year 2019 marked a crucial step towards the completion of the BIPM Kibble balance for realizing the new kilogram definition.

The uncertainty due to misalignment was significantly reduced after the integration of a new interferometer, which is firmly mounted on the magnetic circuit. The electrical grounding of the whole apparatus has been improved, the measurement sequence has been optimized and the apparatus control and data processing software has been refined.

Thanks to METAS (Switzerland), a new measurement of the gravitational acceleration has been carried out with an absolute gravimeter. As a consequence, the relative standard uncertainty has been reduced to about 5 × 10−8. This will allow the BIPM to participate in the first key comparison of realizations of the new definition of the kilogram, CCM.M-K8.2019.

Accord pratique entre le BIPM et l'OTICE

Following the CIPM Decision CIPM/108-38 of October 2019 the Practical Arrangement between the BIPM and the Preparatory Commission of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) on collaboration on the metrological traceability of measurements of infrasound, seismic activity and radioactivity was signed by Dr Lassina Zerbo, Executive Secretary of the CTBTO, on 4 May 2021 and by Dr Martin Milton, Director of the BIPM, on 10 June 2021.

The BIPM assists the CTBTO in its role to provide its States Signatories with data and products of the highest quality standard including reaching compatibility and adherence to the International System of Units (Système International d'Unités, the SI), metrological traceability and measurement uncertainty. The CTBTO assists the BIPM in its role of coordinating the development and validation of Calibration and Measurement Capabilities (CMCs) for measurements in the field of low-frequency sound and vibration as well as radionuclide particulates and gases.

Pursuant to this Practical Arrangement representatives of the BIPM will be invited to attend meetings of the CTBTO related to metrological traceability and measurement uncertainty, including the coordination of Pilot Studies and the development and validation of CMCs. Likewise representatives of the CTBTO will be invited to attend the meetings of the Consultative Committee for Acoustics, Ultrasound and Vibration (CCAUV) and the Consultative Committee for Ionizing Radiation (CCRI).

Le nouveau site internet du BIPM

Bienvenue sur le nouveau site internet du BIPM !

Le design du site a été mis à jour et nous espérons que vous pourrez naviguer plus facilement sur cette nouvelle interface, en particulier sur les petits écrans.

Pour accéder aux contenus en accès restreint (tels que les documents de travail des réunions auxquelles vous avez participez), connectez-vous au site en cliquant sur "CONNEXION" en haut de page. Lors de votre première connexion, cliquez "Mot de passe oublié" puis entrez votre adresse électronique et suivez les instructions envoyées par courriel afin de réinitialiser votre mot de passe.

Pour toute question concernant vos données de connexion, merci de contacter webmaster (a)

Quelques indications importantes :

  1. pour le CIPM MRA et la base de données du CIPM MRA (KCDB), consultez Coordination / CIPM MRA
  2. pour le programme CBKT, consultez À propos / Mission et objectifs
  3. pour trouver un Comité ou un Groupe de travail, consultez Coordination / Comités consultatifs du CIPM ou Liaison / Comités communs
  4. pour les ressources métrologiques internationales, consultez Publications/Réunions puis Ressources métrologiques

Vous ne trouvez pas ce que vous cherchez ? Essayez notre moteur de recherche avancé ! Les résultats comprennent désormais les données du site (y compris les documents de travail disponibles), de Metrologia, de la KCDB et du JCTLM. Si les premiers résultats sont trop nombreux, vous pouvez les filtrer en fonction de l'une des quatre sources puis selon le type de contenu (dans le menu de gauche).

Bonne visite de notre nouveau site !

Si vous rencontrez des problèmes, veuillez contacter webmaster (a)

Vers une transition de l’arséniure de gallium au graphène pour la réalisation de l’ohm à partir de l’effet Hall quantique au BIPM

Since the last revision of the SI, quantum Hall resistance standards (QHR) have been used to perform a direct realization of the ohm from the Planck constant and the elementary charge. These QHR standards are used in a growing number of NMIs even though the cost and complexity of their implementation remains high, mainly due to the technology relying on GaAs/AlGaAs heterostructures that require a very low temperature (<1.5 K), a high magnetic field from superconducting magnets (usually >10 T) and expensive liquid helium to operate.

However, the development and continuing improvement of graphene-based QHR standards during the last decade is now offering an alternative to GaAs based standards. Graphene QHR standards have the remarkable ability to be quantized for less stringent experimental conditions both regarding temperature and magnetic flux density. Quantization of graphene QHE samples has been demonstrated for flux density of 5 T or below and temperature up to 4.2 K.

Replacing GaAs QHR standards by graphene-based standards would bring a significant simplification in the implementation of these primary resistance standards as well as a reduction of their utilization costs and size. This is particularly interesting for the BIPM within the framework of its onsite QHR comparison programme BIPM.EM-K12.

The BIPM has recently had the opportunity to study a new graphene-based QHR sample developed by PTB within the framework of the Graphene Impedance Quantum Standard (GIQS) EURAMET project [1,2]. This sample was fabricated from a homogeneous monolayer of epitaxial graphene of millimetric size whose fabrication has been optimized and on which a molecular post-growth doping technique has been applied to reduce the electron density to values below 1011 cm−2. It is encapsulated within polymer layers and stable working points are expected for low magnetic flux density values below 6 T.

The precision measurements carried out at the BIPM consisted mainly of a verification of the equivalence between this newly developed PTB graphene sample and existing BIPM GaAs references, the graphene sample being operated at liquid helium temperature, 4.2 K, and low magnetic flux densities below 5 T. The graphene QHR was compared, in dc, to a GaAs QHR reference standard through the measurement of a 100 Ω classical transfer resistance. This comparison has been repeated for different current values and with two different GaAs samples of two different fabrication sources.

The differences measured between graphene and GaAs-based QHR samples were found to be very small of the order of (1 ± 3) nΩ/Ω for magnetic flux densities of the graphene sample as low as 4 T, demonstrating the high accuracy the new PTB graphene sample. The stability over time of its carrier density remains to be evaluated. However, regarding the latter point, it has been demonstrated by the PTB and GIQS project partners that the carrier density of the same type of graphene sample can remain stable for a long time and after travelling internationally over long distances between several metrology institutes, provided it is kept enclosed in a container filled with inert gas.

Another type of commercially available graphene-based sample using fabrication processes developed at NIST was also tested at the BIPM, prior to the PTB sample. This sample whose carrier density can be tuned by annealing to the desired value before use [3,4] gave good results and is another very promising candidate for the development of the next generation of QHR standard at the BIPM.

Based on these encouraging results, the transition from the actual GaAs-based QHR reference to a compact graphene-based reference, allowing relaxed operational conditions, is now underway at the BIPM and is planned to be effective in a few years’ time. In the meantime, the study of other graphene-based samples from other sources and/or improved versions of the existing samples will continue, in particular regarding the stability of their carrier density over time or their ability to be easily tuned before use.

  1. GIQS project website:
  3. T. Oe et al., Comparison Between NIST Graphene and AIST GaAs Quantized Hall Devices, IEEE T. Instrum. Meas., 69(6), 2020, 3103-3108 doi: 10.1109/TIM.2019.2930436
  4. A. F. Rigosi et al., Metrological Suitability of Functionalized Epitaxial Graphene 2020 Conference on Precision Electromagnetic Measurements (CPEM), 2020, 1-2, doi: 10.1109/CPEM49742.2020.9191783

Rethinking and modernizing international rulemaking to design better policies for the 21st century

Dr Martin Milton, Director of the BIPM, together with heads of other international organizations (IOs), participated as a panelist in the OECD high-level virtual tour de table: "Rethinking and modernizing international rulemaking to design better policies for the 21st century". The virtual meeting was held on 13 September 2021 as part of the 8th Annual Meeting of International Organisations within the context of the IO Partnership.

Following the high-level event, breakout sessions on technical expert level were held on 14 September 2021 and the BIPM was a moderator of the Breakout session 1: Enhancing the inclusiveness of international rulemaking to discuss follow-up work of the IO Compendium in regard to stakeholder engagement and co-ordination across IOs.

The Compendium of International Organisations' Practices : Working Towards More Effective International Instruments, available at, the first common tool developed collaboratively by some 50 IOs to improve the quality was launched during the 8th Annual IO Meeting. The IO Compendium lists the BIPM practices such as World Metrology Day, CBKT Programme, CIPM MRA Review, JCGM, etc. in five core focus areas. The BIPM is represented in WG2 (implementation of international instruments), WG4 (evaluation of international instruments) and WG5 (IO coordination – as a focal point).

The OECD established the Partnership of international organisations for effective international rulemaking (IO Partnership) as a voluntary platform of IOs, academics and OECD Regulatory Policy Committee delegates, to exchange good practices and promote greater quality, effectiveness, and impact in international rulemaking.

For more information on the 8th Annual Meeting of International Organisations please see:

Protocole d'accord entre le BIPM et CODATA

A Memorandum of Understanding (MoU)between the BIPM and the Committee on Data (CODATA) of the International Science Council (ISC) was signed by Dr Martin Milton, Director of the BIPM and by Dr Simon Hodson, Executive Director of CODATA on 11 October 2021.

The BIPM hosts the CODATA TGFC portal on the BIPM website. The public section of this website provides information about the activities of the CODATA TGFC including meeting dates, meeting minutes, and membership. The BIPM makes its meeting rooms available for meetings of the CODATA TGFC.

The CODATA TGFC assists the BIPM in its role related to the development of the SI, which is now largely based on fixed numerical values of fundamental constants. The CODATA TGFC promotes the consistent use of the SI, in particular by expressing the recommended values of the adjusted constants in SI units. Similarly, the BIPM promotes consistent use of the latest CODATA recommended values of the basic constants.

Pursuant to this MoU a representative nominated by the CIPM will be invited to attend meetings of the CODATA TGFC as the BIPM liaison. The BIPM becomes a partner member of CODATA and will have the right to send a voting delegate to the CODATA General Assembly. Likewise representatives of the CODATA TGFC will be invited to attend the meetings of the Consultative Committee for Units (CCU).

Publication plus rapide des CMCs en chimie et biologie sur la plateforme de la KCDB 2.0

The time taken from submission to publication of internationally recognized measurement capabilities in the fields of Chemistry and Biology has been reduced with the application of the web-based KCDB 2.0 platform, as reported by the CCQM Key Comparison and CMC Quality Working Group (KCWG). On average, over 300 calibration and measurement capabilities (CMCs) in Chemistry and Biology are reviewed each year at the intra-regional and inter-regional level, with the KCDB 2.0 platform allowing time savings in this process to be achieved.

The inter-regional review process for CMCs for chemical and biological measurements is coordinated by the CCQM KCWG. During 2020 and 2021, the annual face-to face meetings of this group were replaced by on-line meetings and the use of the KCDB 2.0 web platform for the review of chemistry and biology CMCs was introduced.

The adoption by the CCQM of the KCDB 2.0 platform in 2021 was underpinned by preparatory work commencing the previous year. This preparatory work included the organization of BIPM Capacity Building and Knowledge Transfer Programme (CBKT) training sessions for potential CMC writers, reviewers and regional metrology organization (RMO) technical committee (TC) Chairs, as well as mock review exercises. In parallel, an instruction document was prepared for CCQM JCRB review using the platform and the CMC review guidelines developed by the CCQM KCWG were reviewed with the support of the KCDB Office.

During 2021, the first batch of CMCs for Chemistry and Biology have been processed and published with the KCDB 2.0. The new procedure allowed the time taken between submission for inter-regional review (JCRB) to publication of the CMC to be reduced to 60 days. A key improvement in the process, recognized by the CCQM KCWG, is the ability of the KCDB 2.0 system to allow individual processing of the CMCs avoiding delays to the completion of review of other CMCs in the same batch.

The BIPM CBKT continues to support national metrology institute (NMI) and designated institute (DI) staff that are new to the KCDB 2.0 process, with the following planned training sessions:

14 October 2021

Online technical exchange: KCDB 2.0 - CMC Writers in Chemistry and Biology

For registration, please contact your RMO Secretariat.

26 January 2022

Online technical exchange: KCDB 2.0 – TC Chairs in Chemistry and Biology

Initiative CBKT : webinaire sur le CIPM MRA pour les participants au projet de détachements BIPM–TÜBİTAK UME

The activities of the fourth cycle of the CBKT initiative - BIPM–TÜBİTAK UME project placements started on 6 September 2021.

The participants for cycle four are from Albania, Bosnia and Herzegovina, Colombia, Kenya, the Philippines, Russia, Sudan, Thailand and Tunisia. Some of the participants have already started their activities at TÜBİTAK UME’s laboratories in Turkey.

A CIPM MRA webinar was organized on 27 September 2021 as part of the BIPM–TÜBİTAK UME project placements. The aim of the webinar was to equip participants with appropriate knowledge on the CIPM MRA mechanisms. Before the webinar the participants in the fourth cycle completed the CIPM MRA e-learning course, which allowed the webinar to be run in the form of discussion. The second part of the webinar included presentations of the metrological projects by the participants. Each participant described the aims of their projects and future implementation plans at their home institutes.

The BIPM offers its thanks to TÜBİTAK UME for its ongoing support for the project placements and we wish the participants good luck during their placements and for the future when implementing their plans.



BIPM e-Learning webpage


Rapport de la 28e réunion du CCRI (2021)

Publié le 20 août 2021.

Supplément 2020 : Activités des départements du BIPM

Published on 13 July 2021

20e Congrès international de métrologie - CIM 2021

The registration for the 20th International Metrology Congress which will be held in Lyon (France) from 7 to 9 September is now open. You will find the complete scientific and technical programme - including more than 200 presentations and 6 round tables - as well as many other practical details about the congress at

Notice that, due to the worldwide pandemic situation, the registration to a web version of the congress will also be possible soon, including videos and live presentations.

Quick access to the registration form

Quick access to the scientific and technical programme

Stratégie du CCQM 2021-2030

Atelier sur la métrologie dans le cadre de la thérapie par radionucléides

Safe and effective cancer therapy using ionizing radiation is only possible due to accurate measurement of the radiation dose delivered to the tumour and surrounding tissues. These measurements are particularly complex for radionuclide therapy and involve measuring the activity of the radionuclide administered to the patient, determining the distribution of the radiopharmaceutical in the body and estimating the radiation dose delivered. This field, which combines biology, dosimetry and radionuclide metrology, is at an early stage.

To mark World Metrology Day, the Consultative Committee for Ionizing Radiation (CCRI) and the Bureau International des Poids et Mesures (BIPM) are organizing a workshop on metrology for radionuclide therapy. The aim is to identify the current needs and gaps in metrology. Speakers are from the NIST, the University of Würzburg, the Medical University of Marburg, the NPL and the IAEA.

The workshop will be on 20 May 2021, 11:00-13:00 UTC. Please register in advance using this link:

Nouvelle plateforme d'e-learning lancée par le BIPM

The BIPM has launched an e-learning platform for staff from NMIs/DIs of Member States and Associates. The platform offers tailored courses to the global metrology community related to scientific metrology activities, including the CIPM MRA mechanisms. The NMI/DI community will have access to the platform around the clock and on any device. You can access the platform by clicking this link:

The first course, introducing the CIPM MRA, is now available.

Lancement d’un Groupe spécifique sur les comparaisons des échelles de concentration des gaz à effet de serre afin d’accroître l’accessibilité aux étalons permettant la surveillance du CO2 atmosphérique et l’authentification des sources d'émission

A task group for Greenhouse Gas Scale Comparisons has been established within the CCQM Working Group on Gas Analysis (CCQM-GAWG) with the goal of increasing global accessibility to standards for underpinning long-term monitoring and emissions authentication of CO2 in the atmosphere with internal consistency of 0.01 μmol/mol over the amount fraction range from 400 μmol/mol to 800 μmol/mol.

Setting up and evaluating a robust economic system based on the mitigation of carbon dioxide is expected to require multiple measurement sites around the world, including around urban areas. This is expected to increase world-wide demand for appropriate CO2 in air gas standards. The CO2 scale system enables the production and value assignment of standards that have very small uncertainties in relationship to each other. This high degree of consistency is important for atmospheric monitoring applications where small temporal and spatial changes are important. The reported consistency between tertiary standards is of the order of 0.01 μmol/mol. The best-known example of the scales approach is provided by the WMO, with the SI traceability of their primary standards demonstrated in the recent CCQM-K120 comparison. This relationship between standards in the scale approach is maintained in a database, and the value of any standard can be traced back to the primary standard set defining the scale.

The CCQM-GAWG chaired by P. Brewer (NPL, UK), includes the WMO Central Calibration Laboratory, maintained at NOAA ESRL GML (USA), and National Metrology Institutes that are active in working towards establishing facilities for CO2 scale standard provision, with a requirement that differences in scales must be close to the internal consistencies which are currently achieved by the WMO scale approach. To minimize any potential scale bias, it is planned to maintain scale equivalence equations by using CIPM MRA on-going key comparisons.

CCQM-GAWG Task Group on GHG Scale Comparisons (CCQM-GAWG-TG-GHG) is chaired by J. Carney (NIST, USA) and supported by reference and comparison facilities maintained within the BIPM laboratories. This includes the CO2-PVT manometric reference facility developed at the BIPM with visiting scientists from NIST (USA) and RISE (Sweden) and validated in the CCQM-P188 comparison. The facility will be the basis for future on-going comparisons of CO2 in air standards (BIPM.QM-K2) ensuring SI traceability of assigned values and comparisons of CO2 in air scales (BIPM.QM-K5) to ensure their consistency at the 0.01 μmol/mol level.

BIPM Manometric reference facility for the comparison of carbon dioxide in air standards. The facility was developed at the BIPM together with visiting scientists from the NIST (USA) and the RISE (Sweden), and operates through the principal of cryogenic separation of CO2 from air samples, with measurement of pressure, temperature and volume of both samples. Initially validated in the CCQM-P188 and CCQM-K120 comparisons, the facility will provide reference values for the future on-going BIPM.QM-K2 comparison of CO2 in air standards, allowing on-demand comparisons of NMI/DI standards anywhere in the range of 380 μmol/mol to 800 μmol/mol, as well as comparison of CO2 in air scale standards (BIPM.QM-K5).

Lancement d'un programme en ligne de transfert de connaissances sur la métrologie pour la sécurité alimentaire, notamment sur les calibrateurs

The BIPM has launched its on-line knowledge transfer courses and studies on Metrology for Food Safety focusing on primary reference materials and calibration solution characterization. The first course covers ‘Quantification of Non-structurally Related Impurity Content in Organic Pure Materials’, previously provided as an on-site course for National Metrology Institutes and Designated Institutes developing mycotoxin standards for food testing applications.

The goal of the course is to transfer knowledge and practical experience on the implementation of Elemental analysis, Thermal Gravimetric Analysis, Karl Fisher Titration, Sorption Balance, and VOC analysis methods for the accurate quantification of non-related structure impurities in pure organics and applicable to mycotoxin materials, and further information can be found at:

Quantification of non-structurally related impurity content in organic pure materials

The Metrology for Food Safety Capacity Building and Knowledge transfer programme, which started in 2016, is designed to allow NMIs to work together to strengthen mycotoxin metrology infrastructure; provide knowledge transfer to scientists developing capabilities in this area, including periods as visiting scientists at the BIPM; and enable NMIs to provide mycotoxin calibrant and matrix reference materials and proficiency test materials to support mycotoxin testing laboratories within their countries.

The project has support from a number of NMIs who are providing scientific expertise and raw materials to the project. The technical activities at the BIPM focus on Mycotoxin Calibrants and providing appropriate training and knowledge transfer.

The first series of on-site knowledge transfer activities were completed in 2020, and BIPM activities for the period 2021-2024 are focused on demonstrating equivalence of Mycotoxin Standards provided by NMIs/DIs through the coordination of CCQM comparisons on mycotoxin calibration solutions for aflatoxin B1, deoxynivalenol, patulin and ochratoxin A. Guidelines for the purity evaluation and calibrant assessment of mycotoxin primary reference materials and calibration solutions are also being made available.

The knowledge transfer programmes have been transferred to on-line versions using the BIPM’s e-learning platform in 2021. The first course to be on-line will be for ‘Measurement of non-related structure impurities in organic pure materials’, with the first module available in May 2021.

Nouveau président du JCTLM

Dr Greg Miller has been appointed Chair of the Joint Committee for Traceability in Laboratory Medicine (JCTLM), taking over from Prof. Ian Young who recently completed his two-year term as Chair.

Dr Miller is a Professor in the Pathology Department at Virginia Commonwealth University where he serves as Co-director of Clinical Chemistry and Director of Pathology Information Systems.  His professional interests and research have focused on standardization and harmonization of laboratory results, quality control and external quality assessment/ proficiency testing. His current professional activities include: Associate Editor of the journal Clinical Chemistry, Chair of the Working Group for Commutability in Metrological Traceability of the International Federation of Clinical Chemistry and Laboratory Medicine, Chair of the Laboratory Working Group of the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health (US), a member of the Harmonization Oversight Group of the International Consortium for Harmonization of Clinical Laboratory Tests, a member of the US delegation to ISO Technical Committee 212 for Clinical Laboratory Testing and In Vitro Diagnostic Test Systems, and other work groups for clinical laboratory standards. 

Dr Miller is a past-president of the American Association for Clinical Chemistry and of the Clinical and Laboratory Standards Institute.  He received the Outstanding Lifetime Achievement Award in Clinical Chemistry and Laboratory Medicine from the American Association for Clinical Chemistry, the Robert Schaffer Award for Outstanding Achievements in the Development of Standards for Use in Laboratory Medicine from the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC), and the Russell J. Eilers Memorial Award from the Clinical and Laboratory Standards Institute.

Most recently Dr Miller has been working with the JCTLM, IFCC, BIPM and International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR) to organize a joint workshop on ‘Overcoming challenges to global standardization of clinical laboratory testing:  reference materials and regulations’, which will be held as a virtual meeting hosted by the BIPM in December 2021.

Documents révisés du CIPM MRA

The documents supporting the CIPM Mutual Recognition Arrangement (CIPM MRA) - the framework through which National Metrology Institutes demonstrate the international equivalence of their measurement standards and the calibration and measurement certificates they issue - have been revised and published on 11 January 2021.

The Arrangement was originally signed in 1999 by 38 Member States and two international organizations and has since matured into a well-recognized pillar of the international quality infrastructure which now covers 258 institutes: signatories from 62 Member States, 40 Associates of the CGPM and four international organizations as well as 152 further institutes designated by the signatory bodies.

To cover the needs of international stakeholders in the nine core Metrology areas, the Arrangement has been supplemented by various clarifications and interpretations which previously amounted to 27 documents. To ensure sustainability after a decade and a half of successful operation, the 25th Meeting of the CGPM (2014) invited a review of the implementation of the Arrangement and to streamline its operation within the existing framework.

The international review of the Arrangement was undertaken in 2016 with a series of recommendations agreed in 2018. This initiated a process to consolidate and update the supporting documents. The revised suite, which was reviewed by both the Consultative Committees and the Regional Metrology Organizations prior to approval by the JCRB, now collates the information in three policy and three guidance documents:

The previous set of documents will be stored at the BIPM and available through the JCRB Members' working area or the JCRB Executive Secretary.

Début d'une nouvelle phase de dissémination du kilogramme

The new definition of the kilogram, based on the fixed numerical value of the Planck constant, came into force on 20 May 2019. It gives in principle any National Metrology Institute (NMI) the possibility to realize the kilogram by using a Kibble or joule balance or by applying the X-ray crystal density technique. Nevertheless, the Consultative Committee for Mass and Related Quantities (CCM) had decided in 2017, after reviewing the results from the different realization experiments, that initially the dissemination of the kilogram shall be internationally coordinated, by basing it on the so-called 'consensus value', until the dispersion between values became compatible with the individual realization uncertainties. The consensus value can be seen as an internationally agreed mean kilogram realization and is determined by the CCM Task Group on the Phases for the Dissemination of the Kilogram. It is based on results of comparisons of kilogram realizations using the different realization methods.

The first key comparison of realizations of the kilogram, CCM.M-K8.2019 has been completed. The objectives of this comparison were to determine the level of agreement between kilogram realizations from different NMIs and to provide information for the calculation of the first CCM consensus value. The CCM started CCM.M-K8.2019 soon after the new definition of the kilogram came into force.

The BIPM was chosen as the pilot laboratory, as it had been for the CCM pilot study in 2016. Seven institutes, including the BIPM, participated with realizations based on Kibble balances, a joule balance and the X-ray crystal density technique. Each participant determined the mass of one or two 1 kg standards under vacuum with their realization method. At the BIPM all mass standards were compared in a vacuum mass comparator with a reference standard. These weighings, together with the mass values determined by the participants, allowed a comparison of the consistency of the individual realizations. The chi-squared test for consistency using the 95 % cut-off criterion was passed, although the two results with the smallest uncertainty were not in agreement with each other (see figure). The weighted mean of the participants' results for a 1 kg mass standard deviates by −0.019 mg from the value based on the BIPM 'as-maintained' mass unit, which is traceable to the International Prototype of the Kilogram (IPK). The results are available from the BIPM Key Comparison Database.

The CCM Task Group on the Phases of the Dissemination of the kilogram has calculated the consensus value as the arithmetic mean of the results of the calibration campaign using the IPK in 2014 [1], the CCM pilot comparison of kilogram realizations in 2016 [2] and the key comparison reference value of CCM.M-K8.2019 [3]. The consensus value for the mass of the IPK thus determined is 1 kg — 0.002 mg [4]. The standard uncertainty is 0.020 mg. Traceability for the SI unit of mass will be taken from the consensus value of the kilogram commencing 1 February 2021.

Since the consensus value is consistent with the value of 1 kg within its uncertainty, no adjustment of the international mass scale needs to be made. However, NMIs with CMCs below or close to 0.020 mg at the level of 1 kg will need to increase their calibration uncertainty.

The BIPM will continue to provide calibrations of 1 kg Pt-Ir prototypes and stainless steel mass standards for Member States, which will be traceable to the Planck constant through the consensus value.

CCM.M-K8.2019: Differences Δmi between mass values attributed to a 1 kg mass standard using the realization experiments of the participants and the key comparison reference value (KCRV), calculated as the weighted mean. The difference between mass values based on the BIPM working standards, traceable to the Planck constant h through the IPK, and those based on the KCRV is also shown as h(IPK).


  1. M. Stock, P. Barat, R. Davis, A. Picard, M. Milton, "Calibration campaign against the International Prototype of the kilogram: Part I: comparison of the International Prototype with its official copies" Metrologia 52 (2015) 310-316.
  2. M. Stock, P. Barat, et al., "Comparison of future realizations of the kilogram" Metrologia 55 (2018) T1-T7.
  3. M. Stock, P. Conceição, et al., "Report on the CCM key comparison of kilogram realizations CCM.M-K8.2019" Metrologia 57 (2020) Tech. Suppl. 07030.
  4. CCM Task Group on the Phases for the Dissemination of the kilogram following redefinition, " Calculation of the Consensus Value for the Kilogram 2020", available from the BIPM web site.

Rapport de la 24e réunion du CCPR (2019)

Publié le 2 février 2021.