### 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. 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. The unit has since largely been replaced by the SI unit: candela per square meter.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.

## 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