candela per square metre

SI coherent derived unit

Name	Symbol	Quantity	Base units
candela per square metre	m⁻² cd	luminance	m⁻² cd
The candela per square metre, symbol m⁻² cd, is the SI coherent derived unit of luminance.
Definition			h c^-2 Δν_Cs⁴ K_cd
$1 \mspace{4mu} \text{m}^{-2} \mspace{4mu} \text{cd} \mspace{6mu} = \dfrac{(299 \mspace{4mu} 792 \mspace{4mu} 458)^2}{(6.626 \mspace{4mu} 070 \mspace{4mu} 15 \times 10^{-34})(9 \mspace{4mu} 192 \mspace{4mu} 631 \mspace{4mu} 770)^4(683)} \mspace{6mu} \dfrac{h \mspace{4mu} {\Delta \nu _{Cs}}^4 \mspace{4mu} K_{cd}}{c^2}\\ \\ \\ 1 \mspace{4mu} \text{m}^{-2} \mspace{4mu} \text{cd} \mspace{6mu} \approx 2.781 \mspace{4mu} 027 \mspace{4mu} 075 \mspace{4mu} 972 \mspace{4mu} 537 \mspace{4mu} 548 \times10^{7} \mspace{6mu} h \mspace{4mu} c^{-2} \mspace{4mu} {\Delta \nu _{Cs}}^4 \mspace{4mu} K_{cd}$

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

candela	cd	luminous intensity
lumen	lm	luminous flux
lux	lx	illuminance
candela per square metre	cd/m²	luminance
lumen second	lm s	luminous energy
lumen per watt	lm/W	luminous efficacy