Illuminance Converter
Enter an illuminance in any common unit and see it in all the others instantly: lux (lx, lumen per square metre), kilolux (klx), millilux (mlx), foot-candle (fc, lumen per square foot), phot (ph, lumen per square centimetre) and milliphot (mph). The value is converted to lux internally using the exact definition of the foot (1 ft² = 0.09290304 m²), so conversions are precise. Useful for lighting design and workplace standards (lux in most of the world, foot-candles in the US), photography and cinematography light meters, plant-growing setups and photometry lab work. Everything is computed locally in your browser.
mlx (millilux)
500,000
lx (lm/m²)
500
klx (kilolux)
0.5
fc (lm/ft²)
46.45152
mph (milliphot)
50
ph (lm/cm²)
0.05
How to use
- Type an illuminance value.
- Pick the unit you entered it in.
- Read the value in every other unit and copy whichever you need.
Frequently asked questions
- How do I convert lux to foot-candles?
- Divide by 10.763910417, because one foot-candle is one lumen spread over a square foot and a square foot is 0.09290304 m². So 500 lx ≈ 46.5 fc, and 1 fc ≈ 10.76 lx. A rough mental shortcut is to divide lux by 10.
- What illuminance is normal indoors and outdoors?
- Roughly: full daylight 10,000–25,000 lx, overcast day about 1,000 lx, a well-lit office 300–500 lx, a living room 50–150 lx, twilight around 10 lx and a full moon about 0.25 lx. Office standards are usually written as 300–500 lx, or 30–50 fc in the US.
- Is lux the same as lumens?
- No. A lumen is total light output; lux is how much of it lands on a surface — one lux is one lumen per square metre. The same lamp gives fewer lux the farther away or the more spread out the light is, which is why lux always refers to a specific surface.
- What are phot and nox?
- They are CGS-era units: one phot is one lumen per square centimetre, so 1 ph = 10,000 lx, and a milliphot is 10 lx. The nox is used for very low light and equals one millilux, so it is the same value as the mlx row here.
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