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.



NIST's work in the metric space includes

  • basic research, such as our work on the redefinition of the SI (International System of Units, commonly known as the metric system)
  • a metric program that helps implement the national policy to establish the SI as the preferred system of weights and measures for U.S. trade and commerce. The metric program provides leadership and assistance on SI use and conversion to federal agencies, state and local governments, businesses, trade association, standards development organizations, educators, and the general public.

The Research

Projects & Programs

Additional Resources Links


Elizabeth Gentry holding a kilogram test weight in the weights and measures training lab

Busting Myths about the Metric System

This year will be the 45th anniversary of the Metric Conversion Act, which was signed on December 23, 1975, by President Gerald R. Ford. Normally, we celebrate by sharing metric education resources, but this year I want to use the occasion to dispel some common misconceptions about the U.S. relationship with the metric system. You’ve probably heard that the United States, Liberia, and Burma (aka
Graphic Image of Weights and Measurements Featured Collection

Discover NIST Education Resources!

World Metrology Day Poster Graphic Image

Celebrate World Metrology Day on May 20

Person holding wallet card showing the values of fundamental constants being used for revising the International System of Units, the modern metric system.

Bringing the World Closer to Revised Measurement System, Scientists Update Four Key Fundamental Constants

Upcoming Events