How Much Electricity Does a Light Bulb Use?
So how much electricity 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 similar light output. That difference means switching bulb types has one of the best cost-to-effort ratios of any change in the house — use the calculator below to compare what your specific bulbs cost to run.
Calculate your cost to run a light bulb
Enter your rate to see your estimate.
What affects how much electricity a light bulb uses
Bulb technology is by far 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 falling in between. Brightness (measured in lumens, not watts, for LEDs and CFLs) determines how much light you get for the wattage. How many hours a day the bulb is actually on, and how many bulbs are running at once in a room, 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.
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.