What Is Lux in Lighting?

Sunlight has the highest lux levels.

Several terms and techniques are specific to lighting. "Lux" is a lighting term used to measure the levels of light received from natural and artificial sources.

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.

References

• University Of Pennsylvania Computer & Information Science Dept.: Basic Principles
• The Engineering Toolbox: Illuminance - Recommended Light Levels
• Compu Phase: Candela, Lumen, Lux: The Equations; T. Riemersma; November 2010