candela per square metre

SI coherent derived unit

Name

Symbol

Derived quantity

candela per
square metre

m⁻² cd

luminance

Definition

The candela per square metre, symbol m⁻² cd, is the SI coherent derived unit of luminance.

Luminance

Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted or reflected from a particular area, and falls within a given solid angle.

Photometry units

Name	Symbol	Quantity	Expressed in terms of SI base units	Expressed in terms of other SI units
candela	cd	luminous intensity	cd	lm/sr
lumen	lm	luminous flux	cd	cd sr
lux	lx	illuminance	m^-2 cd	lm/m²
candela per square metre	m^-2 cd	luminance	m^-2 cd	cd/m²
lumen second	lm s	luminous energy	s cd	lm s
lumen per watt	lm W^‑1	luminous efficacy	kg^‑1 m^‑2 s³ cd	lm/W