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Lumen and Kelvin

Brightness and light colour of a lamp

Once, a light bulb’s consumption value in watts was related to a particular brightness. Nowadays, with the myriad types of lighting (halogen, energy-saving lamp, LED), the wattage is only related to the consumption value.  In order to define a lamp’s lighting performance, two aspects are compared – brightness in lumen and light colour in Kelvin.


Brightness is measured in lumen. Lumen is a measurement of emittance, describing the light a lamp emits. In the graphic, you can ascertain which luminosity is comparable to the wattage of a conventional light bulb.

6000lm 300 W
4000lm 200 W
2000lm 150 W
1300lm 100 W
900lm 75 W
700lm 60 W
400lm 40 W
200lm 25 W
100lm 15 W


A light’s colour is decisive for the ambience and well-being a light creates. This is measured in Kelvin. Warmer light colours for a cosy atmosphere have 2,000 to 3,000 Kelvin. Offices are usually illuminated with neutral light colours with 3,300 to 5,500 Kelvin. Daylight-white lamps are found in factories or salesrooms. The higher the Kelvin, the colder the light effect. Awareness of these differences can be useful when planning your lighting, structuring rooms or creating attractive accents by playing with light colours. 

9999K Blue sky
7000K Overcast sky
5200K Midday sun
4000K Workplace light
3000K Halogen lamp
2700K Light bulb
1500K Candle

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