Foot Candle Calculator

PHOTOMETRY, BEAM, COLOR & UNITS

A foot-candle is one lumen falling on one square foot — the customary measure of illuminance in the US. Calculate it from total lumens and area, or from a point source using candela and distance in feet.

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Foot-candles (fc)
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Lux
Lumens method: fc = lumens divided by area in square feet. Point-source method: fc = candela divided by distance in feet squared.

Two ways to find foot-candles

For an area, divide the delivered lumens by the area in square feet. For a single fixture aimed at a point, the inverse-square law gives foot-candles as candela divided by the distance (in feet) squared.

Foot-candles to lux. Multiply foot-candles by 10.764 to get lux. So 35 fc is about 377 lux.

See the Foot Candle Formula and the Recommended Foot Candle Levels.

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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.