Convert illuminance units — lux, foot-candle, phot, nox and more.
| Unit | Name | Value |
|---|---|---|
| lx | Lux | 0.001 |
| fc | Foot-candle | 0.00009290313 |
| ph | Phot | 1e-7 |
| nx | Nox | 1 |
| klx | Kilolux | 0.000001 |
Formula: Foot-candle = Millilux × 9.2903e-5
Multiply any Millilux value by 9.2903e-5 to get Foot-candle.
Reverse: Millilux = Foot-candle × 1.076e+04
Common illuminance levels — factor: 1 mlx = 9.2903e-5 fc
| Millilux (mlx) | Foot-candle (fc) | Context |
|---|---|---|
| 0.1 mlx | 9.290e-06 fc | Moonless overcast |
| 1 mlx | 9.290e-05 fc | Dark countryside |
| 10 mlx | 0.000929 fc | Moonlit night |
| 100 mlx | 0.00929 fc | Full moon |
| 1000 mlx | 0.0929 fc | 1 lx — full moon bright |
| 1e+04 mlx | 0.929 fc | 10 lx — candle |
| 1e+05 mlx | 9.29 fc | 100 lx — corridor |
| 5e+05 mlx | 46.45 fc | 500 lx office |
| 1e+06 mlx | 92.9 fc | 1,000 lx studio |
| 5e+06 mlx | 464.5 fc | 5,000 lx overcast |
| 1e+07 mlx | 929 fc | 10 klx SAD lamp |
| 5e+07 mlx | 4645 fc | 50 klx hazy sun |
| 1e+08 mlx | 9290 fc | 100 klx bright sun |
| 1.000e+09 mlx | 9.29e+04 fc | Very bright |
| 1.300e+11 mlx | 1.208e+07 fc | Tropical sun |
1 mlx = 9.2903e-5 fc.
Key references: 1 lx = 0.0929 fc. 1 fc = 10.764 lx. 1 phot = 10,000 lx.
Multiply result by 1.076e+04 to recover the original mlx value.
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.
Millilux (mlx) equals 0.001 lux and is used for measuring very low light levels in astronomical, military, and low-light imaging applications. Starlight provides about 0.001–0.01 lx (1–10 mlx); a quarter moon about 0.1 lx (100 mlx).
Night vision equipment, wildlife cameras, and low-light sensor testing use millilux. Military specification MIL-STD-1783 specifies cockpit illumination in millilux for night-vision-compatible conditions. Astronomical photometry measures sky background in millilux.
Interesting fact: The minimum illuminance for the human eye to detect is approximately 0.0001 mlx (0.1 μlx), achieved only in the darkest conditions with fully dark-adapted eyes. Rod photoreceptors, responsible for night vision, are about 1,000 times more sensitive than cones.
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.
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 mlx = 9.2903e-5 fc. Reverse: 1 fc = 1.076e+04 mlx.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.