What Is Lux in Lighting?

Lux

• Lux is the measure of luminosity or the intensity of the visible light striking a surface. One lux is equal to one lumen per square meter. Formerly expressed in Hefner Candlepower, now luminosity is commonly expressed as lux.

Producing Lux

• Lux is produced by natural means or by artificial sources. The sun is a natural source that gives off the highest lux levels, while flames from fire give off a lower lux level. Light bulbs are artificial means of producing lux; different types of bulbs give off different lux levels.

Relative Lux Measurement

• A full moon on a clear night gives off around 0.1 lux. Sunlight has a lux of around 100,000, while daylight on a clear day measures around 10,000 lux. Most household lighting is around 150 lux. A candle 8 inches away gives off light measuring 10 to 15 lux.