How much does a space heater cost to run?
At the current average residential rate of 18.34¢ per kWh, a typical 1,500 W space heater costs about 28¢ per hour — around $25.03 a month and $300 a year at 21 hours a week.
The rate and formula behind these numbers
kWh = watts × hours ÷ 1,000, and cost = kWh × rate. The yearly figure assumes the same weekly pattern all year (× 52); the monthly figure is the yearly one ÷ 12.
Electricity rate: 18.34¢ per kWh — the US EIA Electric Power Monthly for June 2026, the latest month EIA has published (US average across all states). Source: US EIA Electric Power Monthly. Checked September 2, 2026. It excludes the fixed monthly customer charge, which you pay regardless of use.
Nearly every plug-in space heater tops out at the same wattage, because that is as much as a standard household outlet will safely carry — which means ceramic, oil-filled and infrared models all cost the same per hour at full blast, whatever the box claims. What actually changes the bill is how much of the hour the heater spends switched on: a thermostat in a small closed room lets it idle, while an open-plan space keeps it working. Heating one occupied room this way can beat running central heat for the whole house; leaving it on in an empty one never does.