How illuminance converter works
Illuminance — how much light lands on a surface — is measured in lux (lumens per square meter) in most of the world and foot-candles (lumens per square foot) in the US. Lighting designers, photographers and indoor farmers cross between them constantly: a fixture spec in foot-candles, a light meter reading in lux. This converter translates any of the six units into any other.
Every conversion is anchored to the lux using exact definitions: the international foot is exactly 0.3048 m, so one square foot is exactly 0.09290304 m² and one foot-candle is exactly 10.7639104167 lux. The phot, the CGS unit (one lumen per square centimeter), is exactly 10,000 lux, and one lumen per square inch is 1,550.0031 lux. The tool normalizes your value through lux, so both directions of every pair agree.
Results are reported to 12 significant digits, with the intermediate value in lux shown for every conversion so you can check magnitudes at a glance — office lighting of 500 lux is 46.45 foot-candles, direct sunlight near 100,000 lux is 9,290 foot-candles, and a moonlit night around 0.2 lux is 0.019 foot-candles. All math runs in your browser.