Online Lumens to watts Calculator

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Lumens to watts calculator

Enter luminous flux in lumens: lm
Enter light source:
Or enter luminous efficacy in lumens per watt: lm/W
Power result in watts: W

Lumens to watts

Old light sources such as incandescent bulbs or halogen lamps were easy to choose. Here the wattage was the most important indicator for the brightness. If a 60W bulb fails, it could be simply replaced by a new 60W bulb. The replaced lamp was just as bright as before and there was no need to worry about the correct brightness.

For LED lamps, the power consumption is also indicated in watts. However, the wattage plays a minor role now and allows only a very rough conclusion on the actual brightness. Different components in various LED lamps lead to varying brightness with the same power consumption.

For example, a 5W LED illuminant of type A can light up much brighter than a second 5W LED lamp of type B. This is possible because lamp A could achieve a better efficiency through higher quality components and therefore emits more light. For the comparability of LED lamps the brightness is indicated in lumens.

Lumens to watts calculation formula

Energy saving lamps have high luminous efficacy (more lumens per watt).

The power P in watts (W) is equal to the luminous flux ΦV in lumens (lm), divided by the luminous efficacy η in lumens per watt (lm/W):

P(W) = ΦV(lm) / η(lm/W)

Lumens to watts table

Lumens Incandescent
light bulb
 / LED
375 lm 25 W 6.23 W
600 lm 40 W 10 W
900 lm 60 W 15 W
1125 lm 75 W 18.75 W
1500 lm 100 W 25 W
2250 lm 150 W 37.5 W
3000 lm 200 W 50 W

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