Illuminance Converter
Convert lux, kilolux, foot-candles, phot and more. Type in any unit; all others update instantly.
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About This Converter
This illuminance converter supports 8 units used in lighting design, photography, and workplace safety standards. Every calculation passes through a lux base, so results are precise whether you are measuring office lighting in lux, photographic exposure in foot-candles, or scientific readings in phot. It is a handy tool for lighting designers, photographers, architects, and engineers.
FAQ
What is illuminance?
Illuminance measures the amount of luminous flux (light) falling on a surface per unit area. The SI unit is the lux (lx), which equals one lumen per square meter. Higher illuminance means a brighter surface.
What is the difference between lux and foot-candle?
Lux is the metric unit (1 lumen per square meter), while a foot-candle is the imperial equivalent (1 lumen per square foot). 1 foot-candle equals approximately 10.764 lux. Foot-candles are commonly used in the US for architectural and workplace lighting standards.
How much lux is needed for an office?
Most workplace standards recommend 300 to 500 lux for general office tasks such as reading and writing. Detailed work like drafting may require 500 to 1,000 lux. Corridors and lobbies typically need only 100 to 200 lux.
What is a phot and when is it used?
A phot (ph) equals 10,000 lux and belongs to the CGS system. It is rarely used in everyday applications but may appear in older scientific literature. For reference, direct sunlight provides roughly 10,000 lux (1 phot).