Lux to Watts Calculator

Illuminance in lux (lx) to electric power in watts (W) calculator.

Lux is the accepted scientific term for illumination, but the corresponding unit in English and American traditional units is the foot-candle. One Lux is the amount of illumination for 1 lumen per square meter. One foot candle is the amount of illumination for 1 lumen per square foot, or about 10.764 lux which is the number of square feet per square meter. Since one foot-candle is the illuminance cast on a surface by a one-candle source one foot away, a lux could be thought of as a "meter-candle", although this term is discouraged because it does not conform to SI standards for unit names, mainly because candles vary in size (wick size) and amount of light emmitted from the flame, i.e, smaller flame, smaller amount of light.

The foot-candle is commonly used in lighting layouts in parts of the world where United States customary units are used, mainly the United States. Recommended Illuminance Values for Generic Types of Activities in Interiors

Enter the illuminance in lux, luminous efficacy in lumens per watt, surface area in square feet / meters or spherical radius in feet / meters and press the Calculate button to get the power in watts:

Enter illuminance in lux	lx
Select light source
Or enter luminous efficacy in lumens per watt	lm/W
Enter surface area
Or enter spherical radius



Power result in watts	W

Illuminance (lux)	Surfaces illuminated by
0.0001	Moonless, overcast night sky (starlight)
0.002	Moonless clear night sky
0.05–0.3	Full moon on a clear night
3.4	Dark limit of civil twilight under a clear sky
20–50	Public areas with dark surroundings
50	Family living room lights
80	Office building hallway/toilet lighting
100	Very dark overcast day
150	Train station platforms
320–500	Office lighting
400	Sunrise or sunset on a clear day.
1000	Overcast day;[4] typical TV studio lighting
10,000–25,000	Full daylight (not direct sun)
32,000–100,000	Direct sunlight