![NIST's platinum-iridium kilogram K92 (front) with stainless-steel kilogram masses in the background. Credit: J.L. Lee/NIST](../sites/default/files/styles/full_width_image_700x400max/public/media/images/2018/kilogrampic.png%3Fitok=4nh1ZTlC)
NIST's platinum-iridium kilogram K92 (front) with stainless-steel kilogram masses in the background.
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..