– the intergovernmental organization through which Member States act together
     on matters related to measurement science and measurement standards.
Search facility:

| Site map | News | Contact us | [ FR ]
The essential points of the CIPM MRA

The CIPM MRA was drawn up by the International Committee of Weights and Measures (CIPM), under the authority given to it in the Metre Convention, for signature by directors of the NMIs of Member States of the BIPM and Associates of the CGPM.


  • to establish the degree of equivalence of national measurement standards maintained by NMIs;
  • to provide for the mutual recognition of calibration and measurement certificates issued by NMIs;
  • thereby to provide governments and other parties with a secure technical foundation for wider agreements related to international trade, commerce and regulatory affairs.
  • international comparisons of measurements, to be known as key comparisons;
  • supplementary international comparisons of measurements;
  • quality systems and demonstrations of competence by NMIs.


  • statements of the measurement capabilities of each NMI in a database maintained by the BIPM and publicly available on the Web.


NMI directors sign the CIPM MRA with the approval of the appropriate authorities in their own country and thereby:
  • accept the process specified in the MRA for establishing the database;
  • recognize the results of key and supplementary comparisons as stated in the database;
  • recognize the calibration and measurement capabilities of other participating NMIs as stated in the database.


  • signature of the MRA engages NMIs but not necessarily any other agency in their country;
  • responsibility for the results of calibrations and measurements rests wholly with the NMI that makes them and is not, through the MRA, extended to any other participating NMI.

Organizational structure

  • overall coordination is by the BIPM under the authority of the CIPM, which is itself under the authority of the Member States of the BIPM;
  • the Consultative Committees of the CIPM, the Regional Metrology Organizations and the BIPM are responsible for carrying out the key and supplementary comparisons;
  • a Joint Committee of the Regional Metrology Organizations and the BIPM (the JCRB) is responsible for analysing and transmitting entries into the database for the calibration and measurement capabilities declared by the NMIs.

CIPM MRA docs.
Policy documents
Guidance on CMCs
Guidance on comparisons
Complementary info.
Use of the CIPM MRA logo
See also: JCRB
KCDB leaflet
Approval process
Historical development of the CIPM MRA
Organizational structure of the CIPM MRA
The essential points of the CIPM MRA
Potential economic impact of the CIPM MRA
Reports on the KCDB

Official and explanatory texts