Lumens to watts calculator

Luminous flux in lumens (lm) to electric power in watts (W) calculator.

Enter the luminous flux in lumens, luminous efficacy in lumens per watt and press the Calculate button to get the power in watts:

* the predefined luminous efficacy values are typical / average values.

Lumens to watts calculation formula

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

P_(W) = Φ_V(lm) / η_(lm/W)

watts = lumens / (lumens per watt)

W = lm / (lm/W)

What is the power consumption of a lamp that has luminous flux of 900 lumens and luminous efficacy of 15 lumens per watt (lm/W)?

P = 900 lm / 15 lm/W = 60 W

Light type	Typical luminous efficacy (lumens/watt)
Tungsten incandescent light bulb	12.5-17.5 lm/W
Halogen lamp	16-24 lm/W
Fluorescent lamp	45-75 lm/W
LED lamp	80-100 lm/W
Metal halide lamp	75-100 lm/W
High pressure sodium vapor lamp	85-150 lm/W
Low pressure sodium vapor lamp	100-200 lm/W
Mercury vapor lamp	35-65 lm/W

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

Lumens	Incandescent light bulb watts	Fluorescent / LED watts
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

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

Power result in watts:		W

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