Illuminance Converter

If the abundance of lighting units puzzles you, this lumen calculator will undoubtedly come in handy. You may use it to convert between the 8 most common illuminance units: Millilux, Lux, Kilolux, Lumen per square meter, Lumen per square centimeter, Footcandle, Phot, and Nox.

What is illuminance?

Illuminance is a measurement of the amount of light that shines on a particular unit of the surface area of an item. This value is determined by the human perception of the brightness of different wavelengths of light, which correspond to distinct colors. Because humans see the light of roughly 550 nanometers (green) and near to it (yellow and orange) as brighter, the light of longer or shorter wavelengths (purple, blue, red) as darker, illumination estimates are modified for each wavelength. Illuminance is frequently used to describe how bright an item appears to the human eye.


Illuminance can be defined as


E = Φ / A (1)


E = illuminance, light intensity (lm/m2, lux)

= luminescent flux - the amount of light emitted by a light source (lumen, lm)

A = area (m2)

Light Level - Illuminance Measuring Units

In the Imperial system, illumination is measured in foot candles (ftcd, fc, fcd) or lux in the metric SI system.

1-foot candle equals 1 lumen per square foot of light density

1 lux equals 1 lumen per square meter

1 lux equals 1 lumen per square metre = 0.0001 phot = 0.0929 foot-candle (ftcd, fcd)

1 photon Equals 1 lumen per square cm = 10,000 lumens per square metre = 10,000 lux

1 foot candle (ftcd, fcd) equals 1 lumen per square foot = 10.752 lux

How to use the illuminance converter tool?

  • Enter the value in the relevant field. 
  • If you don't immediately discover the desired unit, click on any unit icon to see a list of different units to pick from. 
  • Then click on calculate, and this illuminance converter will automatically complete the necessary conversions into the remaining units.