Technology/ LED Terminology


LED Terminology

Luminous Flux (lm)

Luminous flux (or luminous output) simply states how much light a light source emits. The unit of luminous flux is lumen (lm) and replacements for traditional incandescent bulbs are defined according to this value.

Luminous flux values of various incandescent bulbs:

Traditional bulb (W)
15
25
40
60
75
100
150
LED - Luminous flux (lm)
136
249
470
806
1055
1521
2452

 

Colour Rendering Index CRI (Ra)

Colour Rendering Index says how faithfully a light source shows colour. Both maximum and ideal value equals 100, however, CRI around 80 is considered as absolutely sufficient. 

 

 

 

Colour Temperature (K)

Colour temperature or colour of light is stated in kelvins (K) and says into which colour spectrum the light of a source or fitting falls. Practically, it means how warm the light seems to us and the rule there is simple - the more kelvins, the cooler light. Warm white colour of light is typical for incandescent bulbs, corresponds with 3000 K and is suitable into rooms intended for relaxation or resting. For work or activities when our eyes are strained, e.g. reading, neutral white (around 4000 K) or cool white (around 5000 k) are better.