Work out illuminance (lux) instantly with clear inputs, formula shown and shareable results.
Illuminance is luminous flux per square metre, and one lux is one lumen per square metre. 2000 lumens spread over 8 m2 gives 250 lux, adequate for a living room but short of the 500 lux an office desk needs. Illuminance falls as the lit area grows, which is why ceiling height matters as much as lamp output.
Illuminance
E = luminous flux / area
Unit relation
1 lx = 1 lm/m2 = 0.0929 foot-candles
Roughly 100-200 lux for circulation, 300 lux for living areas, 500 lux for office work and 750-1000 lux for detailed tasks.
Because lux depends on how far away and over what area the light falls. Lumens describe the lamp; lux describes the situation.