Mareld Pro Lighting

Lux, Lumen, Luminans and Candela

The difference between Lux, Lumen, Luminance and Candela

How many lumens a lamp has is often an important part of the decision-making process when choosing work lighting. But what exactly is the difference between Lux, Lumen, Luminance and Candela? We sort out the units for you.

Lumen is the SI unit of luminous flux and has the unit symbol lm. ​Lumen is a measure of luminous flux and describes how much light a lamp emits in total in all directions.

Candela is the SI unit of brightness with the symbol cd. ​The unit one candela is defined as the brightness in a given direction from ​a light source.

Luminance indicates how much light is reflected to our eyes from an illuminated surface. It is measured in candela per square meter (cd/m²).

Lux is the SI unit for illuminance. Illuminance is stated in lux (lx) and is measured with a luxmeter. The luxmeter measures the light that hits the measuring cell. A lux is defined as one lumen per square meter. Illuminance is always given as an average value of several measurements evenly distributed over a measurement area.​​

Things to remember

  • Many manufacturers promise a much larger amount of lumens than the product delivers.
  • Look for how many lumens not how many watts
  • Lumens measure the total luminous flux emitted
  • Lux measures light intensity 
  • Lumen is not the same as perceived light quality

Comparison between products and how many lumen they have

  • Mobile phone 50 lumen
  • 40W ligh- bulb 450 lumen
  • Tellus 1000 Re 1000 lumen
  • H7 Halogen headlights 1500 lumen
  • Orion Re 2500 lumen
  • Blaze 3500 3500 lumen