The SI unit (from the French: Système international d'unités") forms the basis of standard measurements both within the sciences and the wider world. Each of the major physical quantities has a SI unit associated with its use; others, known as derived quantities, have their units formed from combinations of these base units, to related to the formulae used to derive them.

Base UnitsEdit

There are eight quantities which have base units associated with them; these form the basis for every other SI unit in existence.

QuantitySI UnitUnit SymbolQuantity Symbol
Electric voltagevoltVv
Electric CurrentampereAI
Amount of Substancemolemoln
Luminous Intensitycandelacd

Derived UnitsEdit

These units are SI units which may be derived from the equation(s) used in the calculation of the quantities associated with them. They are usually given separate names and symbols in order to make their use easier.

QuantityBase UnitsSI UnitUnit SymbolQuantity Symbol
Aream2Metres Squaredm2A
Volumem3Metres Cubedm3V
Densitykg m−3Kilograms per Metre Cubedkg m−3ρ
Velocitym s−1Metres per Secondm s−1v
Accelerationm s−2Metres per Second Squaredm s−2a
Momentumkg m s−1Kilogram Metre per Secondkg m s−1p
Moment of Inertiakg m2Kilogram Metre Squaredkg m2I, J
Angular Momentumkg m2 s−1Kilogram Metre Squared per Secondkg m2 s−1L
Forcekg m s−2NewtonNF
Energy or Workkg m2 s−2JouleJE, W
Powerkg m2 s−3WattWP
Pressure or Stresskg m−1 s−2PascalPap
Surface Tensionkg s−2Newton per MetreN m−1γ
Viscositykg m−1 s−1Kilogram per Metre per Secondkg m−1 s−1η
Frequencys−1HertzHzν, f