The Metric Act of 1866 says, The metric system of measurement shall be defined as the International System of Units as established in 1960, and subsequently maintained, by the General Conference of Weights and Measures, and as interpreted or modified for the United States by the Secretary of Commerce.
That interpretation is provided by the National Institute of Standards and Technology (NIST), the agency designated by the Department of Commerce with that responsibility.
The interpretation
The most recent interpretation was published in the Federal Register on (73 FR 28432). It announces that two NIST Special Publications serve as the US interpretation of SI, and refers the reader to them: the 2008 editions of
- NIST SP 330, The International System of Units, which is the Americanized version of BIPM’s SI Brochure; and
- NIST SP 811, Guide for the Use of the International System of Units, which provides more extensive guidance on usage of SI, particularly in scientific and technical contexts.
Copies of the NIST publications are available from NIST. The Federal Register notice is available here.
Last updated: