Base unit of measurement

This article is about the type of unit of measure. For the concept in number theory, see Fundamental unit (number theory).

A base unit of measurement (also referred to as a base unit or fundamental unit) is a unit of measurement adopted for a base quantity. A base quantity is one of a conventionally chosen subset of physical quantities, where no quantity in the subset can be expressed in terms of the others. The SI base units, or Systéme International d'unités, consists of the metre, kilogram, second, ampere, kelvin, mole and candela.

A unit multiple (or multiple of a unit) is an integer multiple of a given unit; likewise a unit submultiple (or submultiple of a unit) is a submultiple or a unit fraction of a given unit.[1] Unit prefixes are common base-10 or base-2 powers multiples and submultiples of units.

While a base unit is one that has been explicitly so designated,[2] a derived unit is unit for a derived quantity, involving the combination of quantities with different units;[1] several SI derived units are specially named. A coherent derived unit involves no conversion factors.

  1. ^ a b "ISO 80000-1:2009". International Organization for Standardization. Archived from the original on 2019-07-02. Retrieved 2019-09-15.
  2. ^ Taylor, Barry N.; Thompson, Ambler (2008). The International System of Units (SI). Washington, D.C.: U.S. Department of Commerce. p. 56 (10th CGPM, 1954, Resolution 6).