Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

The new kilogram definition and its implications for high-precision mass tolerance classes



Zeina J. Kubarych


The SI unit of mass, the kilogram, is the only remaining artifact definition in the seven fundamental quantities of the SI system. It will be redefined in terms of the Planck constant as soon as certain experimental conditions recommended by the Consultative Committee for Mass and Related Quantities (CCM) are met. The redefinition will increase the uncertainties that National Metrology Institutes (NMIs) pass on to customers via artifact dissemination, which could have an impact on the reference standards that are used by secondary calibration laboratories if certain weight tolerances are adopted for use. This paper will compare the legal metrology requirements for precision mass calibration laboratories after the kilogram is redefined, with the current capabilities based on the International Prototype Kilogram (IPK) realization of the kilogram.
Journal of Research (NIST JRES) - 118.016
Report Number


mass, kilogram, OIML, metrology


Kubarych, Z. (2013), The new kilogram definition and its implications for high-precision mass tolerance classes, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed July 13, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created August 26, 2013, Updated November 10, 2018