Lux to Foot-candle Calculator
Convert between lux (the SI unit of illuminance, lm/m²) and foot-candles (the US/imperial unit, lm/ft²). One foot-candle equals 10.7639 lux — an exact relationship derived from the definition of a square foot.
Convert from
lx
1 foot-candle = 10.7639 lux (exact SI/imperial conversion)
- 1
Conversion factor: 1 fc = 10.7639 lx
10.7639 - 2
Foot-candles = lux ÷ 10.7639
1,000 ÷ 10.7639 = 92.9030
How does this calculator work?
Lux and foot-candles both measure illuminance (lm per unit area). The conversion is exact: 1 fc = 10.7639 lx, because 1 ft² = 0.09290304 m². Divide lux by 10.7639 to get foot-candles; multiply foot-candles by 10.7639 to get lux.
Formula
How this is calculated
Illuminance measures how much luminous flux (light) falls on a surface per unit area. The SI unit is the lux (lx), defined as one lumen per square metre (lm/m²). The US customary / imperial unit is the foot-candle (fc), defined as one lumen per square foot (lm/ft²). Because one square foot is exactly 0.09290304 m² by the international foot definition, the conversion factor is 1/0.09290304 ≈ 10.7639 fc per lux — or equivalently, 1 fc = 10.7639 lx.
Common illuminance benchmarks (approximate): a moonlit night ≈ 1 lx (0.09 fc); a corridor ≈ 100 lx (9 fc); a typical office ≈ 300–500 lx (28–46 fc); a TV studio ≈ 1000 lx (93 fc); an overcast day ≈ 10 000 lx (929 fc); direct sunlight ≈ 100 000 lx (9 290 fc). Lighting codes in the UK, EU, and Australia use lux; US standards (IESNA) and many photography/film contexts use foot-candles.
Note that lux and foot-candles measure illuminance (light falling on a surface), not luminance (light emitted or reflected). They do not directly measure perceived brightness, which also depends on surface reflectance and the spectral sensitivity of the human eye.
Frequently asked questions
The US lighting industry historically adopted the foot-candle because building codes, IESNA (Illuminating Engineering Society of North America) standards, and legacy equipment were built around imperial measurements. Most of the world uses lux, but US engineers still commonly work in foot-candles for architectural and theatrical lighting.
No. Lumens (lm) measure total luminous flux — the total amount of light emitted by a source in all directions. Lux (lm/m²) measures how concentrated that light is on a given surface area. The same number of lumens spread over a larger area gives fewer lux.
IESNA recommends 300–500 lux (28–46 fc) for general office work and 500–750 lux (46–70 fc) for detailed tasks. The European standard EN 12464-1 specifies 500 lux for a typical office workplane.
Also known as
TG we-Calculate Editorial Team. (2026). Lux to Foot-candle Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/lux-to-footcandle-calculator
TG we-Calculate Editorial Team. "Lux to Foot-candle Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/lux-to-footcandle-calculator.
TG we-Calculate Editorial Team, "Lux to Foot-candle Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/lux-to-footcandle-calculator
@misc{wecalculate_lux_to_footcandle_calculator, title = {Lux to Foot-candle Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/lux-to-footcandle-calculator}}, year = {2026}, note = {TG we-Calculate} }
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