High Luminous Flux 5050 PCT White Color 6000-6500k Bridgelux2240

What is lumens?

          In simple terms, Lumens (denoted by lm) are a measure of the total amount of visible light (to the human eye) from a lamp or light source. The higher the lumen rating the “brighter” the lamp will appear.

Lumens and Useful Lumens

For non-directional bulbs such as a globe, golfball or candle shape, the total lumen output is calculated for all directions. With a directional bulb such as GU10 spotlight, the light is emitted in many directions, some of this light (spill light) may not be useful but it is counted in the total lumen rating. To make comparisons fairer and easier the EU has recently introduced a “useful lumens” rating. This is a measurement of useful light emitted in a standardised 90 degree cone (see image). The “useful lumen” rating is normally lower than the total lumen output but has more relevance to a spotlight bulb where useful light is in a forward focussed direction.