Pick your heater setting, hours and state. See the running cost per hour, day, month and winter, and how an electric blanket compares.
Updated September 2026 · Free · No sign-up
What will your space heater cost?
Cost per hour
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Period
Space heater
Electric blanket
Cost = watts ÷ 1,000 × hours × rate. State rates are average residential prices (EIA, July 2026); your bill's all-in rate, delivery charges included, is more accurate. A month is counted as 30 days.
How the math works
A heater's wattage is its power draw. Divide by 1,000 to get kilowatts, multiply by the hours it runs and by your rate per kWh. A 1,500 W heater for one hour is 1.5 kWh; at 18.31¢ that is 27¢. Every electric resistance heater turns electricity into heat at essentially the same efficiency, so the wattage, not the brand or the "eco" badge, sets the cost.
Why 1,500 watts is the common ceiling
Most plug-in heaters top out around 1,500 W because a standard 15-amp, 120-volt household circuit can safely feed about 1,440 W of continuous cord-and-plug load under the electrical code's 80% rule. That makes 1,500 W the practical ceiling for heaters sold for ordinary outlets. Low settings usually sit around 750 to 900 W.
Cutting the cost
Turn the central heat down while you use it. That is the only way a space heater saves money.
Use the thermostat. A heater that cycles off when the room is warm draws less than one on full power all the time. Lower the "element on" figure above to model it.
Heat the person, not the room. An electric blanket or heated throw uses a small fraction of the power.
Check your rate. Your bill's all-in price per kWh can differ from the state average.
How much does it cost to run a space heater per hour?
A 1,500-watt heater on high uses 1.5 kWh an hour. At the July 2026 US average residential rate of 18.31¢ per kWh (EIA), that is about 27¢ an hour. On a 750 W low setting it is about 14¢.
How much does a space heater add to the electric bill per month?
Running a 1,500 W heater on high for 8 hours a day costs about $66 a month at the US average rate. In Louisiana (12.72¢) it is about $46; in California (33.61¢) about $121.
Is an electric blanket cheaper than a space heater?
Yes, by a wide margin. A blanket typically draws around 100 W (check its label) against a heater's 1,500 W, so 8 hours costs about 15¢ at the US average rate instead of about $2.20. It warms you, not the room.
Does a space heater save money over central heat?
Only if it lets you turn the central thermostat down. Heating one room you are sitting in while the rest of the house cools can cut the bill; running it on top of central heat just adds to it.
