Illuminance Converter
Foot-candle (fc)
Definition: A foot-candle (symbol: fc, lm/ft², or ft-c) is a non-SI unit of illuminance used primarily in the United States customary system. It is defined as one lumen per square foot.
History/origin: Historically, it was defined as the illuminance produced on a surface by a standard "spermace candle" (a candle made from whale oil) at a distance of exactly one foot. It was the common unit before metric standardization.
Current use: Foot-candles are still widely used in the United States and the UK by architects, cinematographers, photographers, and stage lighting designers to set up optimal lighting environments.
Lux (lx)
Definition: The lux (symbol: lx) is the SI derived unit of illuminance and luminous emittance. It measures luminous flux per unit area and is equal to one lumen per square meter.
History/origin: The unit comes from the Latin word "lux," meaning light. It was introduced in 1889 and formally adopted into the International System of Units (SI) to provide a standard measure for human-perceived light intensity.
Current use: Lux is the universal standard used to measure indoor and outdoor lighting levels, workplace safety lighting standards, and environmental lighting for plants and animals.
Foot-candle (fc) to Lux (lx) Conversion Table
| Foot-candle (fc) [fc] | Lux (lx) [lx] |
|---|---|
| 0.01 fc | 0.1076391 lx |
| 0.1 fc | 1.07639104 lx |
| 1 fc | 10.7639104 lx |
| 2 fc | 21.5278208 lx |
| 3 fc | 32.2917312 lx |
| 5 fc | 53.819552 lx |
| 10 fc | 107.639104 lx |
| 20 fc | 215.278208 lx |
| 50 fc | 538.19552 lx |
| 100 fc | 1076.39104 lx |
| 1000 fc | 10763.9104 lx |
How to Convert Foot-candle (fc) to Lux (lx)
1 fc = 10.7639104 lx
1 lx = 0.09290304 fc
Example: convert 15 fc to lx:
15 fc = 15 × 10.7639104 lx = 161.458656 lx
Did You Know?
- The term "Foot-candle" is completely literal! Historically, it was defined as the exact amount of light cast by a single standard candle onto a surface exactly one foot away.
- Did you know? Direct, bright sunlight can measure over 100,000 lux, while a typical well-lit office is around 500 lux. On a clear night, the full moon provides only about 0.1 lux of illumination!