How Much Does It Cost to Run a Space Heater?
A typical 1,500 watt space heater costs about 26 cents an hour to run at full power with electricity at 17 cents per kWh: about $2 for an 8-hour day and about $61 for a month of 8-hour days. A heater with a thermostat, which cycles off when the room is warm, costs less. The numbers come from one formula, so you can work out any heater and any electricity price.
The formula
A 1,500 W heater is 1.5 kW. In one hour it uses 1.5 kWh, and at 17 cents per kWh that costs 25.5 cents. Nearly all of the electricity a space heater uses becomes heat in the room, so it makes no difference whether it is ceramic, oil-filled or infrared: the same watts cost the same. The difference is how well each heats you and the room.
Cost by heater size and electricity price
Running at full power for 8 hours a day, for 30 days:
| Price per kWh | 750 W heater | 1,000 W heater | 1,500 W heater |
|---|---|---|---|
| 10 cents | 7.5¢ an hour, $0.60 for 8 h, $18 a month | 10.0¢ an hour, $0.80 for 8 h, $24 a month | 15.0¢ an hour, $1.20 for 8 h, $36 a month |
| 15 cents | 11.3¢ an hour, $0.90 for 8 h, $27 a month | 15.0¢ an hour, $1.20 for 8 h, $36 a month | 22.5¢ an hour, $1.80 for 8 h, $54 a month |
| 20 cents | 15.0¢ an hour, $1.20 for 8 h, $36 a month | 20.0¢ an hour, $1.60 for 8 h, $48 a month | 30.0¢ an hour, $2.40 for 8 h, $72 a month |
| 30 cents | 22.5¢ an hour, $1.80 for 8 h, $54 a month | 30.0¢ an hour, $2.40 for 8 h, $72 a month | 45.0¢ an hour, $3.60 for 8 h, $108 a month |
Use your own watts and price in the appliance electricity cost calculator. The watts are on the label (or multiply amps by volts: 12.5 A at 120 V is 1,500 W). Most plug-in heaters top out at 1,500 W, to stay within what a standard 15 A household circuit (1,800 W) can supply.
The thermostat makes a difference
A heater does not draw full power all day. When the room reaches the set temperature, the thermostat switches it off, and then on again as it cools. If it runs half the time, the cost halves: $30.60 a month for the same 1,500 W heater, against $61.20 if it ran flat out. A heater in a small, well-insulated room cycles much more than one trying to warm a big drafty space.
Is a space heater cheaper than central heat?
Per unit of heat, almost never. Electric resistance heat costs about $49.82 per million BTU at 17 cents per kWh, against about $15.26 for natural gas at $1.45 per therm. For the whole house, electric resistance heat would cost about $2,691 a year in a moderate climate, against $824 for gas (1,800 ft², average insulation).
A space heater can still save money in one case: when you turn the central thermostat down, and heat only the one room you are in. That works best for one person in a small room, for a few hours. If you leave it on in several rooms, or run it all day, it will cost more than the furnace.
Ways to lower the cost
- Use the thermostat and a timer so that it is not heating an empty room.
- Heat a small, closed room and block the draft under the door.
- Seal windows and doors, with weatherstripping or window film, to hold the heat in.
- Check your plan for time-of-use rates: heating at the cheapest hours can lower the price per kWh.
- Do not use an extension cord or a power strip: space heaters draw enough current to overheat them, and they should plug straight into the wall. Keep heaters away from anything that burns, and never leave one running unattended.
To choose a heater for a room, see the space heater size calculator. To compare electric heat with gas, oil, wood and heat pumps for a whole house, use the heating cost comparison calculator.
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