How to use the space heater cost calculator
- Wattage — check the label on the heater. Most plug-in models draw 1,500 watts on high and many have a 750-watt low setting; choose Other for oil-filled radiators, small ceramic heaters or other models.
- Hours per day and days per month — how long the heater actually runs at full power.
- Months in the season — five covers November through March, the winter period the EIA uses in its Winter Fuels Outlook.
- Electricity price — in cents per kilowatt-hour. Divide your last bill's total by the kWh used to get your all-in rate, including delivery charges.
How the cost is calculated
An electric heater's cost depends only on how much power it draws, how long it runs and what you pay per kilowatt-hour:
kWh = watts × hours ÷ 1,000 and cost = kWh × price per kWh
Example: a 1,500-watt heater uses 1.5 kWh every hour on high. At the U.S. average of 18.31¢ per kWh, that is $0.27 an hour. Run it 8 hours a day and it uses 12 kWh, or $2.20 a day. Over a 30-day month that comes to $65.92, and over a five-month winter $329.58.
What electricity costs right now
The default price is the U.S. average residential price for July 2026, 18.31¢ per kWh, from the EIA's Electric Power Monthly (Table 5.6.A), up from 17.45¢ a year earlier. The same table lists every state, and the range is wide, so replace the default with your own rate for an accurate answer. Prices also vary through the year and by plan; time-of-use plans charge more in peak hours.
Monthly cost by hours of use
At 18.31¢ per kWh and 30 days of use:
| Hours per day | 750 W (low) | 1,500 W (high) |
|---|---|---|
| 1 | $4.12 | $8.24 |
| 2 | $8.24 | $16.48 |
| 4 | $16.48 | $32.96 |
| 8 | $32.96 | $65.92 |
| 12 | $49.44 | $98.87 |
| 24 | $98.87 | $197.75 |
Space heater or central heat?
Every electric resistance heater turns practically all the electricity it uses into heat: one watt gives about 3.412 BTU per hour, so a 1,500-watt heater delivers roughly 5,100 BTU per hour whatever its style or price. A space heater saves money when it lets you keep one occupied room warm while turning the thermostat down for the rest of the house. It costs more when it runs on top of a furnace that is heating the whole home anyway. A heat pump, by contrast, moves heat in from outdoors and typically delivers more heat than the electricity it uses, so heating a whole house with plug-in heaters is usually the expensive choice.
Ways to spend less
- Use the low setting once the room is warm: 750 watts costs half as much per hour as 1,500.
- Let the thermostat work. A heater that cycles on and off uses less than the calculator's full-power figure; a plug-in energy monitor shows the real kWh.
- Close the door and heat only the room you're in, and turn the heater off when you leave.
Safety first
The Consumer Product Safety Commission estimates that portable heaters are involved in an average of 1,600 fires a year, with 70 deaths and 150 injuries annually from 2020 to 2022. Its winter safety advice: keep heaters at least three feet from drapes, furniture, bedding and anything else that can burn; plug electric heaters directly into a wall outlet, never into an extension cord or power strip; and turn heaters off when sleeping.
Frequently asked questions
How much does it cost to run a 1,500-watt space heater per hour?
It uses 1.5 kWh an hour, so the cost is 1.5 × your price per kWh. At the U.S. average of 18.31¢ (July 2026), that is about $0.27 an hour, or $2.20 for 8 hours.
Does a space heater use a lot of electricity?
Yes, compared with most plug-in devices. At 1,500 watts it draws about as much as a hair dryer, but it runs for hours instead of minutes, which is why it can add noticeably to a winter bill.
Is the 750-watt setting half the cost?
Per hour, yes: half the watts means half the kilowatt-hours. In a cold room it may need to run longer to keep up, so the saving over a day can be smaller.
Is it cheaper to use a space heater than central heat?
It can be if you heat one room and turn the central thermostat down. Heating a whole house with plug-in heaters usually costs more than a furnace or heat pump.
Are some space heaters more efficient than others?
Not in turning electricity into heat: all electric resistance heaters convert nearly 100% of it. Differences come from thermostats, timers and how the heat is spread around the room.
Last updated: October 8, 2026