What is the Foot-Candles to Lux Calculator?
This calculator converts illuminance measured in foot-candles (fc) into lux (lx), the SI unit of illuminance. A foot-candle is the amount of light (one lumen) falling on one square foot of surface, while a lux is one lumen falling on one square metre. Because one square foot equals 0.092903 square metres, one foot-candle equals exactly 10.7639 lux.
How to use it
Enter your illuminance value in foot-candles and the calculator instantly returns the equivalent in lux. This is useful for lighting designers, photographers, and engineers who work with light meters that read in foot-candles but need metric lux values for IES or EN standards.
The formula explained
The conversion uses a single multiplier: $$\text{Lux} = \text{Foot-candles} \times 10.7639$$ The factor 10.7639 is the number of square feet in one square metre, so spreading the same luminous flux over the larger metric area changes the unit count proportionally.
Worked example
Suppose a light meter reads 50 foot-candles on a desk surface. Multiplying \(50 \times 10.7639\) gives 538.195 lux. That tells you the workspace is lit to roughly 538 lux, which is in the recommended range for general office tasks.
$$50 \times 10.7639 = 538.195 \text{ lux}$$
FAQ
Is the conversion exact? The factor 10.7639 is an accurate rounding of \(1/0.092903\), precise enough for all practical lighting work.
How do I go from lux back to foot-candles? Divide the lux value by 10.7639 (or multiply by 0.0929).
What lux level is typical indoors? Living rooms are around 150–300 lux, offices 300–500 lux, and detailed work areas 750–1000 lux or more.
