# Stilb (unit)

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terms such as candle per square inch and candle per square meter were more common.[2] The unit has since largely been replaced by the SI unit: candela per square meter.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

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

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

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

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

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

Other units of luminance:

SI photometry quantities
Quantity Unit Dimension Notes
Name Symbol[nb 1] Name Symbol Symbol
Luminous energy Qv [nb 2] lumen second lm⋅s TJ [nb 3] Units are sometimes called talbots.
Luminous flux / luminous power Φv [nb 2] lumen (= cd⋅sr) lm J [nb 3] Luminous energy per unit time.
Luminous intensity Iv candela (= lm/sr) cd J [nb 3] Luminous flux per unit solid angle.
Luminance Lv candela per square metre cd/m2 L−2J Luminous flux per unit solid angle per unit projected source area. Units are sometimes called nits.
Illuminance Ev lux (= lm/m2) lx L−2J Luminous flux incident on a surface.
Luminous exitance / luminous emittance Mv lux lx L−2J Luminous flux emitted from a surface.
Luminous exposure Hv lux second lx⋅s L−2TJ
Luminous energy density ωv lumen second per cubic metre lm⋅s⋅m−3 L−3TJ
Luminous efficacy η [nb 2] lumen per watt lm/W M−1L−2T3J Ratio of luminous flux to radiant flux or power consumption, depending on context.
Luminous efficiency / luminous coefficient V 1