Lumens per Watt Calculator

Calculate the luminous efficacy of a light source by dividing its light output by its power consumption.

lumens
watts

Luminous Efficacy

80.0 lm/W

Annual Energy Cost (8hr/day)$4.38
Voir la formule →

Formule

## Luminous Efficacy **Efficacy = Lumens / Watts** Higher efficacy means more light per unit of energy. ### Efficacy Benchmarks - Below 20 lm/W: Poor (incandescent) - 50-70 lm/W: Good (CFL) - 80-120 lm/W: Very good (modern LED) - Above 120 lm/W: Excellent (high-efficiency LED)

Exemple Résolu

800 lumens from a 10 watt LED.

  1. 01Efficacy = 800 / 10 = 80 lm/W
  2. 02Annual cost at 8hr/day: 10W x 8 x 365 / 1000 x $0.15 = $4.38