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 |
| klx | Kilolux | 0.000001 |
| mlx | Millilux | 1 |
Formula: Kilolux = Nox × 1.0000e-6
Multiply any Nox value by 1.0000e-6 to get Kilolux.
Reverse: Nox = Kilolux × 1e+06
Common illuminance levels — factor: 1 nx = 1.0000e-6 klx
| Nox (nx) | Kilolux (klx) | Context |
|---|---|---|
| 0.001 nx | 1.000e-09 klx | Moonless overcast |
| 0.01 nx | 1.000e-08 klx | Dark sky |
| 0.1 nx | 1.000e-07 klx | Moonlit night |
| 1 nx | 1.000e-06 klx | Full moon = 1 mlx |
| 10 nx | 1.000e-05 klx | 10 mlx |
| 100 nx | 1.000e-04 klx | 0.1 lx dim indoor |
| 1000 nx | 0.001 klx | 1 lx full moon bright |
| 1e+04 nx | 0.01 klx | 10 lx |
| 1e+05 nx | 0.1 klx | 100 lx corridor |
| 1e+06 nx | 1 klx | 1,000 lx studio |
| 5e+06 nx | 5 klx | 5,000 lx |
| 1e+07 nx | 10 klx | 10,000 lx SAD lamp |
| 5e+07 nx | 50 klx | 50,000 lx |
| 1e+08 nx | 100 klx | 100,000 lx bright sun |
| 1.300e+11 nx | 1.3e+05 klx | Tropical noon |
1 nx = 1.0000e-6 klx.
Key references: 1 lx = 0.0929 fc. 1 fc = 10.764 lx. 1 phot = 10,000 lx.
Multiply result by 1e+06 to recover the original nx 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.
The nox (nx) is an obsolete unit of illuminance equal to 0.001 lux = 1 millilux, proposed for measuring very low light levels in dim conditions. It was never widely adopted and is not recognized by any current standards body.
The nox was briefly proposed in some mid-20th century photometry literature specifically for mesopic and scotopic (low-light) illuminance measurements where lux values would be very small fractions. It never entered widespread use.
Interesting fact: The nox is one of the rarest photometric units — it rarely appears even in specialty lighting engineering texts. Its value equals exactly 1 millilux, making it redundant once millilux became the preferred notation for low illuminance levels.
Kilolux (klx) equals 1,000 lux and is used for high-illuminance environments including daylight simulation, horticulture, and phototherapy. Direct sunlight registers 80–130 klx; overcast daylight 1–25 klx.
Seasonal affective disorder (SAD) treatment lamps provide 10 klx at close range for 30-minute daily sessions. Horticulture lighting for fruiting plants targets 20–60 klx. Industrial quality control inspection stations may require 5–10 klx.
Interesting fact: The human circadian rhythm is most strongly reset by 10 klx blue-enriched light in the morning. Even 2.5 klx has measurable circadian effects — explaining why indoor living (typically 200–500 lx) can disrupt sleep cycles.
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 nx = 1.0000e-6 klx. Reverse: 1 klx = 1e+06 nx.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.