footcandle

Convert between footcandles and other major units of illuminance.

A unit of illuminance in the foot-pound-second system of units, the illuminance at 1 foot from a 1-candela point source of light. Symbol, Ftc. One footcandle is approximately 10.76391 lux.

Originally the footcandle was the illuminance at 1 foot from a standard candle, then at 1 foot from an international candle. It was next defined as the illuminance produced by 1 lumen of “luminous flux” evenly distributed over a square foot.

Though not an SI unit, footcandles are still widely used to set lighting levels in architecture, in stage lighting, and in photography.