Space Heater Cost Calculator
Enter your heater's watts and the hours it actually heats, pick your state, and get the cost per hour, day, month and heating season.
Space heater cost
A01Scenario A
Sets the electricity rate. Pick US average if you're not sure.
From EIA for US average. Use the rate on your bill if you know it.
Rate used: 18.4¢/kWh · US average · EIA reference 2025–26 (data as of 2026-09-26) ·
Most portable heaters have a 750 W low and a 1,500 W high setting.
Hours the heater is actually on, not hours plugged in. A thermostat makes it cycle.
Estimated cost per month
Cost by month, in season only
The yearly cost spread across the months using a typical heating degree-day pattern from NOAA 1991–2020 normals. Months outside the season show $0.
Per year assumes the same use every day. For seasonal appliances, see the monthly curve.
Estimate. Formula and sources are under “How it works”. Change any input; the result updates as you type.
Formula
How it works
The calculator multiplies the heater's power by the hours it heats and by your state's electricity rate:
- kWh per day = watts ÷ 1,000 × heating hours per day
- Cost per hour = watts ÷ 1,000 × rate
- Cost per month = kWh per day × days in the month × rate
- Cost by month = yearly cost × that month's share of heating degree-days
1,500 W is the most a standard 120 V outlet can deliver continuously: a 15 A circuit × 120 V × 80%. That's why almost every portable heater sold in the US tops out at 1,500 W and has a 750 W low setting. Because the heater's thermostat switches it on and off, enter the hours it actually heats, not the hours it sits plugged in.
Sources: electricity rate from the U.S. Energy Information Administration (EIA), Electric Power Monthly table 5.6.A, residential sector, latest month for your state (shown under the result). Monthly heating pattern from NOAA Climate Prediction Center degree-day normals, 1991–2020.
Worked example
A worked example
A 1,500 W space heater running 6 hours a day in Texas uses 1.5 kW × 6 h = 9.00 kWh a day. At the Texas rate of 15.5¢/kWh, that's $0.23 an hour, $1.40 a day, and $43.24 for a 31-day month. Run it that way every day of the year and it would come to $509.18. Used only in heating season, the estimate is $101.84 in January, $106.93 in December, and $0.00 in July and August.
Reference
Reference table
Space heater cost per month at 18.4¢/kWh (US average), 30 days
| 2 h | 4 h | 6 h | 8 h | 12 h | |
|---|---|---|---|---|---|
| 750 W | $8.28 | $16.56 | $24.84 | $33.12 | $49.68 |
| 1,000 W | $11.04 | $22.08 | $33.12 | $44.16 | $66.24 |
| 1,500 W | $16.56 | $33.12 | $49.68 | $66.24 | $99.36 |
Questions
FAQ
Is it cheaper to run a space heater or central heat?
It depends on how much of the house you need to heat. One 1,500 W heater warming a single room is usually cheaper than running a gas furnace for the whole house, as long as you turn the central thermostat down. Heating several rooms with several heaters usually isn't cheaper. Compare both options with your state's electricity and gas prices in the Space Heater vs Central Heat calculator.
Does a 750 W setting cost half as much?
Yes. Half the watts costs half as much per hour: at the US average rate of 18.4¢/kWh, that's about $0.14 an hour instead of $0.28. It also gives off half the heat, so in a cold room it may run twice as long and cost the same.
How much does a space heater add to my bill per month?
At the US average rate, a 1,500 W heater running 6 hours a day for 30 days adds an estimated $49.68. In Texas at 15.5¢/kWh it's $43.24 for a 31-day month; in California at 32.0¢/kWh, a 750 W heater running 12 hours a day comes to $86.40. Add your heater to My bill to see it next to your other appliances.
How much does it cost to run a space heater all winter?
Look at the 12-month curve under your result. At the US average rate, the 1,500 W, 6-hour example comes to about $121 in January and $127 in December, dropping to $0 in summer, following a typical heating-degree-day pattern.
How do I know how many hours my heater actually runs?
If the heater has a thermostat, it switches off when the room reaches the set temperature. A plug-in power meter shows the real kWh over a day. Divide that by the heater's kW to get effective hours.
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