Lumen to Watt (LED) Calculator

Watts = lumens / efficacy. Modern LEDs hit 100-150 lm/W, vs incandescent ~15 lm/W.

Inputs

LED: 80-150. CFL: 60-70. Halogen: 20. Incandescent: 15.

Result

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General calculation reads

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How to use this calculator

  • Enter desired lumens.
  • Pick efficacy (default 100 for typical LED).
  • Read wattage of LED, plus equivalents in older lighting types.

About this calculator

Lumens measure total light output; watts measure electrical power consumed. Efficacy (lumens per watt) is the conversion. Incandescent ~15 lm/W (mostly waste heat), CFL ~65, LED 80-150. So an 800-lumen "60W equivalent" LED uses about 8-10W.

Frequently asked

How do "60W equivalent" LEDs work?+
A 60W incandescent puts out ~800 lm. The LED matches that lumen output but uses only 8-10W to do it. Marketed as "60W equivalent" but actual draw is much less.
What's the highest LED efficacy?+
Lab record ~300 lm/W. Commercial best ~200 lm/W. Typical home LEDs 80-110 lm/W.
Why are LEDs so much more efficient?+
Direct conversion of electricity to light via semiconductors, very little waste heat. Incandescent loses 90%+ as heat.
Do efficacy numbers degrade over time?+
Yes — LED output drops about 10% over 50,000 hours. Quality LEDs maintain efficacy for years.
Lumens, lux, candela — what's the difference?+
Lumen = total light. Lux = lumens per m² (illuminance on a surface). Candela = directional intensity. Lumen is what you usually want for "how bright is this bulb".

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