– the intergovernmental organization through which Member States act together
     on matters related to measurement science and measurement standards.
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Calibration services

    The primary role of the BIPM's activity in Mass is to provide traceability to the International Prototype of the Kilogram.

    Calibrations of Pt-Ir prototypes and mass standards in stainless steel are carried out each year during the periods March to May and September to November.


    1 kg prototypes in Pt-Ir

      The BIPM offers a calibration service for 1 kg national prototypes in Pt-Ir. This service is available free of charge to Member States. The Physical Metrology Department maintains a number of prototypes and other standards in Pt-Ir. A subset of these are used as working standards to calibrate national prototypes upon request. The remainder are used for quality control. The standard uncertainty currently assigned to the calibration of a national prototype depends on the time since the last use of the IPK. The last use of the IPK was in 2014 and the combined standard uncertainty of the calibration of national prototypes is currently 0.0045 mg.

      The BIPM also fabricates Pt-Ir prototypes for Member States upon request.

    • Request the calibration of a national prototype

    1 kg mass standards in stainless steel

      The BIPM offers a calibration service for 1 kg standards in stainless steel. This service is available free of charge to NMIs of Member States. The volume of the standard will be determined by hydrostatic weighing at the BIPM if this parameter is unknown (typical combined standard uncertainty obtained at the BIPM is 0.44 mm3 at the reference temperature of 20.0 °C). However, the volumetric thermal expansion near room temperature must be supplied by the NMI or the manufacturer of the standard. If not already in our database, the BIPM will determine the location of the centre of gravity of the standard. The combined standard uncertainty currently assigned to the calibration of a 1 kg standard in stainless steel is typically 0.010 mg.

    • Request the calibration of a 1 kg standard in stainless steel