Lux (lx)	Foot-candles (fc)
1 lx	0.0929 fc
2 lx	0.1858 fc
5 lx	0.4645 fc
10 lx	0.929 fc
25 lx	2.3226 fc
50 lx	4.6452 fc
100 lx	9.2903 fc
250 lx	23.2258 fc
500 lx	46.4515 fc
1000 lx	92.903 fc

Illuminance Unit Conversions

Free online illuminance converter. Instantly convert between Lux, Foot-candles, Phots, Nox, Kilolux, and more with exact scientific formulas.

Understanding Illuminance Conversions

The SI unit of illuminance is the lux (lx), which equals one lumen per square meter (1 lx = 1 lm/m²). It quantifies the intensity of light falling on a given surface.

Supported Illuminance Units (5 Units)

Lux (lx) (SI standard illuminance (1 lumen/m²)) — Primary SI / Base Reference Unit
Foot-candle (fc) (US architectural & photography lighting (1 lm/ft²)) — 1 fc = 10.76391 lx
Phot (ph) (CGS optical standard (10,000 lux / 1 lm/cm²)) — 1 ph = 10000 lx
Nox (nox) (Night vision & astronomy optics (1 millilux)) — 1 nox = 0.001 lx
Kilolux (klx) (Direct sunlight & greenhouse horticulture) — 1 klx = 1000 lx

Popular Illuminance Conversions

Lux ⇄ Foot-candle

Multiply lux by ~0.092903 to calculate illuminance in foot-candles (or divide lux by 10.7639).

Foot-candle ⇄ Lux

Multiply foot-candles by ~10.7639 to convert to lux (1 fc ≈ 10.764 lx).

Kilolux ⇄ Lux

1 kilolux equals exactly 1,000 lux (typical overcast daylight is 1–10 klx).

Phot ⇄ Lux

1 phot equals exactly 10,000 lux (1 lumen per square centimeter).

Frequently Asked Questions

Common questions and verified calculations for illuminance units.

How do you convert foot-candles (fc) to lux (lx)?

Multiply the foot-candle value by 10.7639. For example, standard office lighting of 50 fc equals approximately 538.2 lux (50 × 10.7639 ≈ 538 lx).

What is the difference between a foot-candle and a lux?

Both measure illuminance (light falling on a surface). Lux is the metric SI unit (1 lumen per square meter), while foot-candle is the imperial US customary unit (1 lumen per square foot). Because 1 square meter is approximately 10.764 square feet, 1 fc ≈ 10.764 lux.

What are typical real-world light levels in lux?

Direct bright sunlight: 32,000 to 100,000 lux; Overcast day: 1,000 to 10,000 lux; Office or classroom work: 300 to 500 lux; Home living room: 100 to 200 lux; Full moon at night: 0.1 to 0.3 lux.