How much does it cost to run an LED bulb?
We've pre-filled an typical LED bulb below. Set your electricity rate and adjust the hours to match how you use yours — the cost updates instantly.
A single LED bulb is about as close to free electricity as anything in your house. At 9 watts, running one for 5 hours a day costs somewhere around 5 to 8 cents a month at typical US rates — you'd have to burn one nonstop, all day every day, for a year before it added up to a couple of dollars. That's not a rounding error in the marketing; it's the actual math of moving from a 60-watt incandescent filament to a 9-watt diode doing the same job.
The reason it barely shows up on your bill is that LEDs waste almost nothing as heat — touch one after an hour and it's barely warm, while the old incandescent it replaced would burn your fingers. That's roughly 85% less power for the same light output, which is why swapping five bulbs in a room you use every evening saves real money over a year, even though any single bulb's monthly cost rounds to pennies. The savings aren't in turning bulbs off — they're already baked into the bulb.
What drives the cost of running an LED bulb
- Wattage, not bulb count: a 9W LED is fixed, but higher-lumen bulbs (60W-equivalent vs. 100W-equivalent) draw more — check the box, not just the socket
- Hours per day: a hallway light left on 5 hours costs a fraction of a porch light or garage bulb left on 24/7
- How many bulbs are actually LED: rooms with old incandescent or CFL bulbs still mixed in will cost far more per fixture than the LED math suggests
How to cut it
- Turning bulbs off when you leave a room — with LEDs already this cheap, the savings are too small to matter
- Buying "premium" or smart LED bulbs for cost reasons — the wattage difference between LED brands is negligible next to the incandescent-to-LED jump
- Dimming LEDs to save power — most dimmable LEDs don't scale wattage linearly and the savings are pennies either way
Common questions
How much does it cost to run an LED bulb per month?
At a typical 9W and about 5 hours a day, an LED bulb costs roughly $0.23 a month at $0.17/kWh. Set your own rate and hours above for an exact figure.
How can I cut the cost of running an LED bulb?
Turning bulbs off when you leave a room — with LEDs already this cheap, the savings are too small to matter
Does it cost more to run a porch light or closet light 24/7?
Barely. A 24-hour LED (porch light, closet, garage) still only costs about 30-45 cents a month at typical rates — 24/7 on a 9W bulb is under 6.5 kWh a month. It's the one lighting scenario worth switching to a timer or motion sensor for, not because the bulb is expensive, but because it's the rare case where hours actually add up to real kWh.
Does switching an LED on and off a lot use more electricity than leaving it on?
No — LEDs draw their full rated wattage almost the instant you flip the switch, unlike CFLs which pull extra current warming up. Turning an LED on and off doesn't waste anything, so there's no reason to leave it on 'to save power.'
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