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What is UCUM?

Unified Code for Units of Measure (UCUM) is a code system intended to include all units of measures being contemporarily used in international science, engineering, and business.

UCUM Specification

View and download the specification and its source XML. You can also clone the repository.

Requests for Units

Learn how to request new units for potential inclusion in the standard.


Participate in our forum for UCUM developers and implementers. Our discussion space on GitHub is also a good place to get your questions answered.


Learn about use of UCUM through numerous documents about the standard.


UCUM was created by Gunther Schadow and Clem McDonald in 1999. Learn more about its origins.

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