What Is the Lux to Foot-Candles Calculator?
This tool converts illuminance measured in lux (the SI unit, lumens per square meter) into foot-candles (fc), the imperial unit equal to lumens per square foot. Both units describe how much light falls on a surface, but they use different area references, so a simple conversion factor links them.
How to Use It
Enter the illuminance value in lux and the calculator instantly returns the equivalent in foot-candles. This is handy for lighting designers, photographers, and engineers who work with mixed-unit specifications, since many international standards quote lux while US documentation often uses foot-candles.
The Formula Explained
Because 1 square meter equals 10.7639 square feet, one foot-candle equals 10.7639 lux. To convert in the other direction:
$$\text{fc} = \frac{\text{lux}}{10.7639}$$
The constant 10.7639 is simply the number of square feet in a square meter, which is where the area-based unit difference comes from.
Worked Example
Suppose an office is lit to 500 lux, a common target for general office work. Dividing by 10.7639 gives $$500 \div 10.7639 \approx 46.45 \text{ foot-candles}.$$ So 500 lux is roughly 46 fc.
FAQ
Is lux brighter than a foot-candle? No — they measure the same physical quantity (illuminance). One foot-candle is about 10.76 lux, so the same lighting level has a larger lux number and a smaller foot-candle number.
Why 10.7639? It is the exact number of square feet in one square meter (one meter = 3.28084 feet, squared ≈ 10.7639).
How do I convert back? Multiply foot-candles by 10.7639 to get lux.
