Convert illuminance between lux and foot-candles for lighting design, photography, workplace safety, and building specifications.
Illuminance measures how much light falls on a surface. It tells you how brightly a work area, room, or outdoor space is lit.
The SI unit of illuminance is lux (lx), which means lumens per square meter. In the imperial system, illuminance is often measured in foot-candles (fc), which means lumens per square foot.
Since one square meter is larger than one square foot, one foot-candle equals more lux.
Example 1: Convert 100 lux to foot-candles
Step 1: Use the formula
Step 2: Substitute the value
Example 2: Convert 9.290304 foot-candles to lux
Step 1: Use the reverse formula
Step 2: Substitute the value
Note: The foot-candle value (9.290304) is rounded from the initial conversion. Multiplying the rounded value back through the conversion factor yields approximately the original value due to rounding precision.
| lux | fc |
|---|---|
| 1 | 0.092903 |
| 5 | 0.464515 |
| 10 | 0.92903 |
| 20 | 1.858061 |
| 50 | 4.645152 |
| 100 | 9.290304 |
| 500 | 46.451522 |
| 1000 | 92.903044 |
| 10000 | 929.030436 |
| fc | lux |
|---|---|
| 0.092903 | 1 |
| 0.464515 | 5 |
| 0.92903 | 10 |
| 1.858061 | 20 |
| 4.645152 | 50 |
| 9.290304 | 100 |
| 46.451522 | 500 |
| 92.903044 | 1000 |
| 929.030436 | 10000 |
Both measure illuminance. Lux is lumens per square meter, while foot-candles are lumens per square foot.
A square meter covers more area than a square foot, so the same light level corresponds to a larger numeric lux value.
Lux is the international SI standard. Foot-candles are still common in the United States, especially in building, photography, and workplace references.
A typical office target is about 300 to 500 lux, which is roughly 28 to 46 foot-candles.
Yes. Lux and foot-candles are both common in photography, cinematography, and studio lighting workflows.
Those are the underlying unit meanings of foot-candles and lux, so they help clarify what each measurement represents.
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