Lux / Footcandle Converter and Lumen Method
Exact lux <-> footcandle conversion and the lumen-method average maintained illuminance from luminaire lumens, coefficient of utilization, and light-loss factor.
Formula and source
fc = lux / 10.764 (1 footcandle = 1 lumen/ft^2; 1 lux = 1 lumen/m^2; 1 ft^2 = 0.092903 m^2). Lumen method (room average): fc = (total lumens × CU × LLF) / area_ft2, where CU is the coefficient of utilization and LLF the light-loss factor.
IES Lighting Handbook (10th ed.) lumen method, by name; the 10.764 lux-per-footcandle conversion is an exact unit identity.
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