The Unified Code for Units of Measure (UCUM) was developed by Regenstrief Institute and the UCUM Organization as a unambiguous system of units and their combinations. From the UCUM website:

"The 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. The purpose is to facilitate unambiguous electronic communication of quantities together with their units. The focus is on electronic communication, as opposed to communication between humans. A typical application of The Unified Code for Units of Measure are electronic data interchange (EDI) protocols, but there is nothing that prevents it from being used in other types of machine communication."

UCUM has been adopted internationally by many organizations such as IEEE, DICOM, LOINC, and HL7, and is also in the ISO 11240:2012 standard.

The National Library of Medicine provides several resources for working with UCUM:

  • Online validation & conversion of UCUM units. Users can enter UCUM expressions on the page and validate them or convert them to other expressions.
  • Batch validation of UCUM units. Users can submit a CSV (a spreadsheet format) file with a column of UCUM unit expressions, and the validator will return another CSV file with the addition of a column that reports on the validity of each unit expression.
  • Examples of commonly used UCUM codes. This document is based on real-world usage of UCUM in data from Intermountain Healthcare.
  • ucum-lhc: A library providing APIs for validating and converting UCUM units as a downloadable package. Includes a suggestion feature for incorrectly typed units.