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How much does it cost to run a space heater?

At the U.S. average residential price of 18.31¢ per kilowatt-hour (July 2026), running a space heater costs about $158 a year. Your own bill depends on your state's rate, which ranges from 12.72¢ to 48.00¢ across the country.

Assumption: 1,500 W at a 60% duty cycle, 8 hours a day, 120 days a year — 864 kWh a year. 1,500 W is the ceiling for a 120 V plug-in heater, and nearly every model sold hits it on high. A thermostat changes how often it runs, not how hard.

Cost by state

Same appliance, same usage, 51 different prices. Sorted cheapest first.

Cutting the number down

• Heating one occupied room and letting the rest of the house sit cooler is the whole case for a space heater. Running one in every room costs more than central heat.
• Ceramic, oil-filled and infrared heaters all convert essentially 100% of the electricity to heat. At the same wattage the running cost is identical, whatever the box claims.
• The cheapest watt is the one you skip: closing the door to the room you are heating does more than any model upgrade.

Questions

How many watts does a space heater use?

About 1,500 W while running, though it cycles on and off, so average draw is 900 W.

How much does a space heater cost per month?

About $13.18 a month at the U.S. average rate, or $158 a year.

Where is it cheapest to run?

Louisiana, at $110 a year, versus $415 in Hawaii — a spread of $305.