Luminous efficacy — lumens per watt — is the clearest measure of how efficient a light source is. This chart compares the major technologies.
| Source | Efficacy |
|---|---|
| Incandescent | 10 to 17 lm/W |
| Halogen | 16 to 24 lm/W |
| CFL | 50 to 70 lm/W |
| Linear fluorescent | 80 to 100 lm/W |
| Metal halide | 65 to 115 lm/W |
| High-pressure sodium | 80 to 140 lm/W |
| LED (typical) | 120 to 180 lm/W |
| LED (premium) | 200 lm/W and up |
Why LED wins. LED delivers up to ten times the light per watt of incandescent, and the gap widens yearly as chip efficiency improves.
See the Efficacy Formula and Lumens by Lamp Type.