How Much Electricity Does a Light Bulb Use?
How much electricity does a light bulb use? 40 to 100 watts incandescent, about 15 for LED. Enter yours below for the exact cost.
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Light bulb electricity cost calculator
Enter your rate to see your estimate.
How the math works: 60 W × 4 hours ÷ 1,000 = 0.24 kWh a day. × 30 days = 7.2 kWh a month. × $0.165 per kWh (the 2024 U.S. average) = about $1.19 a month.
A traditional incandescent bulb draws 40 to 100 watts depending on brightness, while a comparable LED replacement draws roughly 15 watts for similar light output. For a 60-watt bulb, that gap means switching to LED cuts its running cost by about three quarters.
| Bulb | Typical watts |
|---|---|
| Incandescent | 40-100 W |
| LED replacement (about 800 lumens) | about 15 W |
What affects how much electricity a light bulb uses
- Bulb technology: the biggest factor. LEDs use up to 90% less energy than incandescent bulbs for comparable brightness, according to the U.S. Department of Energy, with CFLs in between.
- Brightness: measured in lumens, not watts, for LEDs and CFLs. Lumens tell you how much light you get for the wattage.
- Hours and bulb count: how many hours a day a bulb is on, and how many run at once, both scale the total cost directly.
How to reduce your light bulb's electricity use
- Replace incandescent bulbs with LED equivalents, which the DOE states use up to 90% less energy for the same brightness
- Turn lights off in rooms nobody's using instead of leaving them on out of habit
- Use dimmers or lower-wattage bulbs in fixtures where full brightness isn't needed
- Take advantage of natural daylight when possible instead of running lights during the day
Typical wattage figure: incandescent 40-100 W typical; a comparable LED replacement runs roughly 15 W for about 800 lumens. Source: U.S. DOE: Lighting Choices to Save You Money; specific example from FTC Consumer Lighting Facts guidance. DOE states LEDs use up to 90% less energy than incandescent bulbs for comparable brightness. We review this figure periodically and update it if the source changes; last checked September 2026. Cedrick Reese built this light bulb cost calculator and rechecks the wattage figure against the source above.
Frequently asked questions
How many watts does a light bulb use?
A traditional incandescent bulb draws 40 to 100 watts depending on brightness, while a comparable LED replacement draws roughly 15 watts for about 800 lumens (equivalent to a 60-watt incandescent), according to U.S. DOE lighting guidance.
How much does it cost to run a light bulb?
A 60-watt incandescent bulb run 4 hours a day at the U.S. average rate of about 16.5 cents/kWh costs roughly $0.04 a day, or about $1.19 a month, versus about $0.30 a month for an equivalent-brightness 15-watt LED. Use the calculator above to compare your own bulbs.
Is switching to LED bulbs really worth it?
For most households, yes. The DOE states LEDs use up to 90% less energy than incandescent bulbs for the same brightness, and LED bulbs also typically last far longer, which further reduces the total cost of lighting a home over time.
How can I reduce how much electricity my lighting uses?
Switch remaining incandescent bulbs to LED equivalents, turn off lights in unoccupied rooms, and use dimmers or lower-wattage bulbs in fixtures where you don't need full brightness.
This page provides estimates based on typical wattage figures and the numbers you enter. Actual electricity cost depends on the specific bulb technology, wattage, and hours of use.