LED Equivalent Wattage Calculator
Convert an old incandescent bulb’s wattage to the equivalent LED wattage by matching lumens, and see the energy saved.
How it works
lumens = incandescent watts × incandescent efficacy · LED watts = lumens ÷ LED efficacy
Brightness is measured in lumens, not watts — watts is just the power drawn. Incandescent bulbs convert only a sliver of that power to light (about 14 lumens per watt), while modern LEDs reach 80–100 lm/W, so an LED needs far fewer watts to produce the same lumens. Matching lumens rather than watts is the correct way to replace a bulb; the wattage on the box is now only a legacy “equivalent” label.
Worked example
A 60 W incandescent at 14 lm/W emits 60 × 14 = 840 lumens. To match that with a 90 lm/W LED you need 840 ÷ 90 = 9.3 W — about 51 W (85%) less power for the same light. That is why a “60 W-equivalent” LED bulb actually draws roughly 8–10 W.
Sources: Luminous efficacy (Wikipedia)
Frequently asked questions
Should I match watts or lumens?
Always lumens. Watts only measures power consumed; two bulbs of the same wattage can differ hugely in brightness. Read the lumen rating on the package and match that to the light you want.
Why do LED “equivalent” numbers vary?
Because LED efficacy keeps improving and manufacturers round differently. A 60 W-equivalent might be 8 W on one brand and 10 W on another; comparing the actual lumens removes the guesswork.
Does color temperature change the wattage?
Not directly — lumens set the wattage for a given efficacy. Color temperature (2700 K warm vs 5000 K daylight) changes how the light looks, and very high-CRI or warm LEDs can be slightly less efficacious, nudging watts up a little.
Related calculators
Educational estimates only — electrical work must follow the National Electrical Code (NEC) and local amendments, and be done or inspected by a licensed electrician.