The measurement of various dimensional properties such as: Length, Area, Volume, Radius of Curvature and Angle are one of the oldest forms of measurement known to man and key to the development of civilization.


Base SI Unit of Length

Since 1983, the meter (metre) has been internationally defined as the length of the path traveled by light in vacuum during a time interval of 1/ 299 792 458 of a second.

SI Derived Units

Derived units are units which may be expressed in terms of base units by means of mathematical symbols of multiplication and division.

Dimension-related derived SI units have been given special names and symbols, and these special names and symbols may themselves be used in combination with the SI and other derived units to express the units of other quantities.

Examples of SI derived Dimensional units expressed in terms of base units
Derived Quantity SI derived unit
Name Symbol
area square meter (metre) m2
volume cubic meter (metre) m3
speed, velocity meter (metre) per second m/s
acceleration meter (metre) per second squared m/s2
wavenumber 1 per meter (metre) m-1
specific volume cubic meter (metre) per kilogram m3/kg
20 °C—A Short History of the Standard Reference Temperature for Industrial Dimensional Measurements; NIST J Res Jan-Feb 2007 112-1; 2007