### Stilb (luminance)

The stilb (sb) is the CGS unit of luminance for objects that are not self-luminous. It is equal to one candela per square centimeter or 104 nits (candelas per square meter). The name was coined by the French physicist André Blondel around 1920.[1] It comes from the Greek word stilbein meaning "to glitter".

It was in common use in Europe up to World War I. In North America self-explanatory terms such as candle per square inch and candle per square meter were more common.[2] The unit has since largely been replaced by the SI unit: candela per square meter. The current national standard for SI in the United States discourages the use of the stilb.[3]

## Unit conversion

$\mathrm\left\{1\, \frac\left\{cd\right\}\left\{m^2\right\} = 10^\left\{-4\right\}\, sb\right\}$

$\mathrm\left\{1\, sb = 1\,\frac\left\{cd\right\}\left\{cm^2\right\} = 10^4\,\frac\left\{cd\right\}\left\{m^2\right\}\right\}$

$\mathrm\left\{1 \, sb = 10^4 \, nit = 10^7 \, millinit\right\}$

$\mathrm\left\{1 \, sb = 1 \pi \, L = 10^3 \pi \, mL = 10^4 \, \pi \, asb = 10^4 \pi \, blondel = 10^7 \pi \, sk = 10^\left\{11\right\} \pi \, bril\right\}$

$\mathrm\left\{1 \, sb = 10^4\,\frac\left\{cd\right\}\left\{m^2\right\} \approx 0.3048^2 \cdot 10^4 \cdot \pi \,\, fL = 2918.6...\, fL\right\}$

Other units of luminance:

• Nit (nit and millinit)
• Apostilb (asb)
• Blondel (blondel)
• Skot (sk)
• Bril (bril)
• Lambert (L and mL aka millilambert)
• Footlambert (fL)

SI photometry units

Quantity Unit Dimension Notes
Name Symbol[nb 1] Name Symbol Symbol
Luminous energy Qv [nb 2] lumen second lm⋅s T⋅J [nb 3] units are sometimes called talbots
Luminous flux Φv [nb 2] lumen (= cd⋅sr) lm [nb 3] also called luminous power
Luminous intensity Iv candela (= lm/sr) cd [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⋅sm−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