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 International System of Units (SI), 2001 Edition



Barry N. Taylor


NIST Special Publication (SP) 330 is the United States version of the English text of the definitive international reference on the International System of Units (SI) published by the International Bureau of Weights and Measures (BIPM) on behalf of the International Committee on Weights and Measures (CIPM). Entitled The International System of Units (sI), it lists all Resolutions and Recommendations of the general Conference on Weights and Measures (CGPM) and of the CIPM on the SI. Further, the text provides explanations of the decisions on the SI made by the CGPM and CIPM and accompanies them with relevant extracts from the International Standards of the International Organization for Standardization. NIST SP 330 also includes editorial comments that do not appear in the original BIPM text, but which further clarify the SI and point out the several differences between the way the SI is interpreted in the United States and the way it is interpreted in other countries.
Special Publication (NIST SP) - 330
Report Number


BIPM, CIPM, International System of Units, measurement, metric system, modern metric system, SI, units


Taylor, B. (2001), The International System of Units (SI), 2001 Edition, Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed July 15, 2024)


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

Created July 1, 2001, Updated November 10, 2018