Convert illuminance units — lux, foot-candle, phot, nox and more.
| Unit | Name | Value |
|---|---|---|
| lx | Lux | 10.7639 |
| ph | Phot | 0.00107639 |
| nx | Nox | 10763.9 |
| klx | Kilolux | 0.0107639 |
| mlx | Millilux | 10763.9 |
Formula: Lux = Foot-candle × 10.76
Multiply any Foot-candle value by 10.76 to get Lux.
Reverse: Foot-candle = Lux × 0.0929
Common illuminance levels — factor: 1 fc = 10.76 lx
| Foot-candle (fc) | Lux (lx) | Context |
|---|---|---|
| 0.0001 fc | 0.001076 lx | Moonless night |
| 0.001 fc | 0.01076 lx | Dark countryside |
| 0.01 fc | 0.1076 lx | Moonlit road |
| 0.1 fc | 1.076 lx | Full moon |
| 1 fc | 10.76 lx | Dark corridor |
| 5 fc | 53.82 lx | Stairway / passage |
| 10 fc | 107.6 lx | Lobby |
| 30 fc | 322.9 lx | Office minimum |
| 50 fc | 538.2 lx | IES office standard |
| 100 fc | 1076 lx | Surgical minimum |
| 200 fc | 2153 lx | Detailed surgery |
| 500 fc | 5382 lx | Close inspection |
| 1000 fc | 1.076e+04 lx | Extreme inspection |
| 5000 fc | 5.382e+04 lx | Hazy sunlight |
| 1.2e+04 fc | 1.292e+05 lx | Bright sun |
fc × 10.764 = lx. Round to × 10.76.
1 fc = 10.76 lx. 50 fc = 538 lx (IES office). 100 fc = 1,076 lx.
lx × 0.0929 = fc.
Specifies illuminance levels in lux (metric) or foot-candles (US) for architectural, retail, and workplace lighting per IES and EN 12464 standards.
Measures scene illuminance in lux with a light meter to set correct exposure for available-light photography.
Verifies that workplace lighting meets minimum requirements (typically 500 lx for offices, 300 lx for corridors) per local regulations.
Monitors grow-light illuminance in klx to optimize plant growth — fruiting plants typically need 20–60 klx.
Prescribes and measures light therapy intensity in lux for SAD treatment (10,000 lx standard) and circadian rhythm research.
Measures ambient light in lux to set appropriate display backlight levels for consistent image quality.
The foot-candle (fc) is the US customary unit of illuminance, defined as one lumen per square foot. One foot-candle = 10.7639 lux. It has been used in North American lighting specifications since the early 20th century and remains standard in US architectural and theatrical lighting.
US lighting standards use foot-candles: Illuminating Engineering Society (IES) specifies office work at 30–50 fc (300–500 lx), surgery at 200–400 fc, and roadway lighting at 0.5–2 fc. Stage lighting designers in North America universally work in foot-candles.
Interesting fact: The foot-candle's name reflects its origin — the illuminance on a surface one foot from a standard candle. The international candle standard was defined in 1909, and American lighting engineers adopted the foot-candle as their practical working unit from that era.
The lux (lx) is the SI unit of illuminance, defined as one lumen per square meter. It measures how much light falls on a surface, regardless of the surface's color or reflectivity. The lux was formally adopted by the International System of Units in 1960, superseding the older phot and metre-candle.
Lux levels define lighting requirements across all domains: emergency lighting minimum 1 lx, corridor lighting 100 lx, office work 500 lx, surgery 10,000–100,000 lx. Outdoor daylight ranges from 1,000 lx (overcast) to 130,000 lx (direct tropical sunlight).
Interesting fact: Human eyes can adapt to a remarkable range — from about 0.001 lx (moonless night) to over 130,000 lx (direct sunlight) — a factor of 100 million. Yet the lighting standards for reading (500 lx) are only 500 times brighter than a typical moonlit night (1 lx).
Illuminance measures light falling on a surface. The SI unit is lux (lm/m²); the US standard is foot-candles (lm/ft²). Key reference levels: moonless night ~0.001 lx, full moon ~1 lx, office work 500 lx, SAD therapy 10,000 lx, bright sunlight 100,000 lx.
Exact factor: 1 fc = 10.76 lx. Reverse: 1 lx = 0.0929 fc.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.