Foot-candles and lux both measure illuminance, the light falling on a surface. They differ only by area unit: 1 foot-candle = 10.7639 lux. Enter a value below to convert, and add an area to size the total lumens.
How to convert foot-candles and lux
To go from foot-candles to lux, multiply by 10.7639. To go the other way, divide by 10.7639. To size lighting, multiply the target level by the area in the matching unit: foot-candles times square feet, or lux times square meters, both give lumens delivered to the surface.
Typical target light levels (guidance)
| Space | Foot-candles | Lux |
|---|---|---|
| Corridor / lobby | ~10 | ~100 |
| General office | ~30 to 50 | ~300 to 500 |
| Retail / classroom | ~50 to 75 | ~500 to 750 |
| Detailed task work | ~75 to 100 | ~750 to 1000 |
Frequently asked questions
How many lux are in a foot-candle?
One foot-candle equals 10.7639 lux. A foot-candle is one lumen per square foot; a lux is one lumen per square meter.
How do I convert lux to foot-candles?
Divide the lux value by 10.7639. So 500 lux is about 46.5 fc, and 1000 lux is about 92.9 fc.
How do I calculate the lumens I need?
Multiply target foot-candles by area in square feet, or target lux by area in square meters. 50 fc over 200 sq ft needs 10,000 lumens before losses.
What is a good light level for an office?
General office work is often designed for about 30 to 50 fc (300 to 500 lux) at the work surface. Check the applicable lighting standard for your space.
Does this account for light loss?
No. The lumens figure is raw light delivered to the surface. Real installs lose light to fixture efficiency, mounting height, and reflectance, so add a margin.
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