Candela per square metre

"Nit (unit)" redirects here. For other uses, see Nit.

The candela per square metre (cd/m²) is the SI unit of luminance; nit is a non-SI name also used for this unit. It is often used to quote the brightness of computer displays, which typically have luminances of 50 to 300 nits (the sRGB spec for monitors targets 80 nits). Modern flat-panel (LCD and plasma) displays often exceed 300 cd/m² or 300 nits.

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The term is believed to come from the Latin "nitere" = to shine.

References

IEC 61966-2-1:1999 is the official specification of sRGB.

SI photometry units
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Quantity	Symbol	SI unit	Abbr.	Notes
Luminous energy	Q_v	lumen second	lm·s	units are sometimes called talbots
Luminous flux	F	lumen (= cd·sr)	lm	also called luminous power
Luminous intensity	I_v	candela (= lm/sr)	cd	an SI base unit
Luminance	L_v	candela per square metre	cd/m²	units are sometimes called nits
Illuminance	E_v	lux (= lm/m²)	lx	Used for light incident on a surface
Luminous emittance	M_v	lux (= lm/m²)	lx	Used for light emitted from a surface
Luminous efficacy		lumen per watt	lm/W	ratio of luminous flux to radiant flux; maximum possible is 683.002 lm/W
Units-interrelation diagram (full page)