lux

Convert between lux and other major units of illuminance.

In SI, the unit of illuminance – how brightly a surface is illuminated. One lux is 1 lumen per square meter. (One lux is about 0.09 foot-candles.) The plural is also “lux”, not “luxes”.

On the Earth’s surface, the illumination from the sun is about 100,000 lux; from a full moon at the zenith on a clear night, about 0.27 lux; and from all the stars about 0.00022 lux.

The lux is a derived unit. In terms of base units, it is

$A fraction. The numerator is candela and the denominator is steradian times meters squared$