Lumen to Watt (LED) Calculator

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

Result

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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".