The Unified Code for Units of Measure (UCUM) is a code system of standardised codes for measurement units used in medicine and pharmacy, based on 7 standard units. This industry standard, in international use since 1999, is published in English by the Regenstrief Institute.
UCUM at Regenstrief Institute

Area of application

Medical documentation IT applications use UCUM for the unambiguous communication of measurements based on standard SI units. Application areas include the representation of:

  • laboratory tests
  • clinical examinations
  • pharmaceutical data

All measured results are consisting of a numerical value and a unit of measurement. At present, IT systems have different ways to represent units of measurement. Measured values transmitted from other applications may be interpreted falsely, and measured data are difficult to compare. A uniform standard such as UCUM could help to prevent this.

UCUM versus International System of Units

The basic units used in UCUM differ in some instances from the international standard metric system of units (Système international d'unités) which is mandatory by law in Germany, too. However, units constructed from UCUM basic units in accordance with the rules can be reduced again to SI units.

Technical implementation and representation

UCUM can represent any number of valid units derived from 7 basic units. To that end, the standard combines various components:

  • Basic units
    • metre (m, length)
    • second (s, time)
    • gram (g, mass)
    • radian (rad, angle)
    • Kelvin (K, temperature)
    • Coulomb (C, electric charge)
    • candela (cd, luminous intensity)
  • derived units with conversion factors and formulas for the reduction to base units
  • prefixes, i.e. a list of 30 standard prefixes to generate multiples (e.g. k for kilo, multiplier 10³) or fractions (e.g. d for deci, multiplier 10-1) of measurement units
  • symbols and operators as well as syntax rules for their combination

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