Watts to Lumens Calculator

Find brightness from wattage and efficacy.

Brightness (lm) 800

Formula: lumens = watts × efficacy

Step-by-step with your numbers:

1. Values used:

2. Power = 10 W

3. Efficacy = 80 lm/W

5. Brightness = Power x Efficacy = 10 x 80 = 800lm

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Convert power to light output using luminous efficacy.

The math behind it

lumens = watts × efficacy (lm/W).

10 W LED at 80 lm/W → 800 lm.

Brightness, not watts?

Shop by lumens — watts only tells you energy use.