Metric SI units

The International System of Units is abbreviated “SI” from the French “le Système international d’unités”. SI is the modern form of the metric system and is a coherent and definable measurement system devised around multiples of ten. It is the planet’s most widely used system of measurement, both for everyday commerce and for engineering, science and technology.

Base SI units

Quantity	Unit	Symbol	Equivalent Unit	Equivalent Unit
Length	metre	m
Mass	kilogram	kg
Time	second	s
Electric current	ampere	A	C/s
Absolute temperature	kelvin	K
Amount of substance	mole	mol
Luminous intensity	candela	cd
Plane angle	radian	rad
Solid angle	steradian	sr
Frequency	hertz	Hz	1/s
Force	newton	N	kg m/s²
Energy	joule	J	Nm
Power	watt	W	J/s	VA
Electric Charge	coulomb	C	As
Voltage – potential difference	volt	V	W/A
Electrical capacitance	farad	F	C/V

Base SI units

Further reading