Light Intensity Converter
Convert between lux, foot-candles, lumens per square meter, and phot for lighting measurements.
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Light intensity (illuminance) measures how much light falls on a surface. All conversions use lux as the base unit.
Unit definitions:
- 1 lux = 1 lumen per square meter (lm/m²)
- 1 foot-candle = 10.7639 lux (1 lumen per square foot)
- 1 phot = 10,000 lux (CGS unit, 1 lumen per cm²)
- 1 nox = 0.001 lux (used for very low light)
Typical illuminance levels:
| Condition | Lux | Foot-candles |
|---|---|---|
| Full moonlight | 0.25-1 | 0.023-0.093 |
| Street lighting | 10-50 | 0.93-4.65 |
| Office lighting | 300-500 | 27.9-46.5 |
| Overcast day | 1,000-2,000 | 93-186 |
| Direct sunlight | 50,000-100,000 | 4,650-9,300 |
Metric (lux) vs Imperial (foot-candles): Most of the world uses lux. The US commonly uses foot-candles for architectural lighting design.