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 irony of the magnet system for Kibble balances -- a review



Stephan Schlamminger, Shisong Lo


The magnet system is an essential component in the Kibble balance, supplying the magnetic flux that plays a vital role as the geometric factor $Bl$. Ironically, the $Bl$ factor cancels out and does not appear in the final Kibble equation. Nevertheless, care must be taken to design and build the magnet system because the cancellation is perfect if the $Bl$ is the same in both modes, the weighing and velocity mode. This review provides the knowledge necessary to build a magnetic circuit for the Kibble balance. In addition, it discusses the design considerations, parameter optimization, practical adjustment to the final performance evaluation, and an assessment of systematic uncertainties associated with the magnet system.


Magnet system, Kibble balance, primary realization of mass


Schlamminger, S. and Lo, S. (2022), The irony of the magnet system for Kibble balances -- a review, Metrologia, [online],, (Accessed May 19, 2024)


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

Created March 1, 2022, Updated November 29, 2022