The candela per square metre (cd/m2) is the derived SI unit of luminance. The unit is based on the candela, the SI unit of luminous intensity, and the square metre, the SI unit of area. Nit (nt) is a deprecated non-SI name also used for this unit (1 nit = 1 cd/m2).[1]
Most consumer desktop liquid crystal displays have luminances of 200 to 300 cd/m2;[2] the sRGB spec for monitors targets 80 cd/m2.[3] HDTVs range from 450 to about 1000 cd/m2.
Nit is believed to come from the Latin nitere, to shine.[4]
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One candela per square metre is equal to:
Quantity | Symbol[nb 1] | SI unit | Symbol | Dimension | Notes | |||
---|---|---|---|---|---|---|---|---|
Luminous energy | Qv [nb 2] | lumen second | lm⋅s | T⋅J | units are sometimes called talbots | |||
Luminous flux | Φv [nb 2] | lumen (= cd⋅sr) | lm | J | also called luminous power | |||
Luminous intensity | Iv | candela (= lm/sr) | cd | J [nb 3] | an SI base unit, luminous flux per unit solid angle | |||
Luminance | Lv | candela per square metre | cd/m2 | L−2⋅J | units are sometimes called nits | |||
Illuminance | Ev | lux (= lm/m2) | lx | L−2⋅J | used for light incident on a surface | |||
Luminous emittance | Mv | lux (= lm/m2) | lx | L−2⋅J | used for light emitted from a surface | |||
Luminous exposure | Hv | lux second | lx⋅s | L−2⋅T⋅J | ||||
Luminous energy density | ωv | lumen second per metre3 | lm⋅s⋅m−3 | L−3⋅T⋅J | ||||
Luminous efficacy | η [nb 2] | lumen per watt | lm/W | M−1⋅L−2⋅T3⋅J | ratio of luminous flux to radiant flux | |||
Luminous efficiency | V | 1 | also called luminous coefficient | |||||
See also: SI · Photometry · Radiometry |