# Definition:SI Units

## Definition

The SI Units are the elements of the International System of Units.

## SI Base Units

SI base units
Name Unit symbol Dimension Symbol
metre $\mathrm m$ Length $l$
kilogram $\mathrm {kg}$ Mass $m$
second $\mathrm s$ Time $t$
ampere $\mathrm A$ Electric Current $I$
kelvin $\mathrm K$ Temperature $T$
candela $\mathrm {cd}$ Luminous Intensity $I_v$
mole $\mathrm {mol}$ Amount of Substance $n$

## SI Derived Units

The units derived from the SI base units include the following:

## Historical Note

The SI units originated in the work done by Joseph Louis Lagrange to establish a decimal system for weights and measures.

## Linguistic Note

The abbreviation SI in the term SI units is from the French Le Système International d'Unités (the International System of Units).