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 Electronic Kilogram



Michael H. Kelley


The kilogram is the only remaining base unit in the International System of Units (SI) whose definition is based on a single physical artifact rather than on fundamental properties of nature. Effects such as environmental contamination or material loss from surface cleaning are causing the true mass of the International Prototype Kilogram to drift (by about 5 parts in 108 per century), relative to sister prototypes. The equivalence of electrical and mechanical power provides a possible alternate measurement of mass in terms of other units that are based on fundamental quantum mechanical principles, such as the speed of light, the Josephson voltage, and the quantum Hall resistance. This provides a possible time-invariant definition of mass.
Proceedings Title
Tech. Dig., IEEE MTT-S International Microwave Symposium
Conference Dates
May 20-25, 2001
Conference Location
Phoenix, AZ


absolute ampere, balance, fundamental constants, kilogram, mass standard, watt


Kelley, M. (2001), The Electronic Kilogram, Tech. Dig., IEEE MTT-S International Microwave Symposium, Phoenix, AZ, [online], (Accessed June 17, 2024)


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

Created May 1, 2001, Updated February 19, 2017