candela per meter
The measure of this brightness is the luminance in candela per square metre6. 2.4.1 Luminance and Brightness We have used the terms luminance and brightness interchangeably.
Luminance is a derived measure, expressed in Candela per square metre (\( cd / m^2 \)). An alias for the unit \( cd / m^2 \) (unofficial, but still commonly used) is Nit. Luminance and illumination (Lux) are related, in the sense that luminance is typically used for light-emitting surfaces and illumination for surfaces that are being lit.