A 1,500-watt space heater, a common rating, costs about 27 cents an hour to run on high at the U.S. average residential electricity price of 18.16 cents per kWh for August 2026. At 8 hours a day for a month, that is about $65. Your number depends on three things: the heater’s wattage, how many hours it actually runs, and what you pay per kWh.
This guide shows the math, works it at low, average and high electric rates, and explains when a space heater saves money and when it only adds to your bill. For your state’s latest rate, see our electricity rates by state.
The Formula
Your bill charges for kilowatt-hours (kWh). The Energy Information Administration (EIA) defines one watt-hour as “the energy of one Watt used for one hour,” and 1 kWh is 1,000 watt-hours.
Cost per hour = (watts ÷ 1,000) × your rate per kWh
Check the label on your heater for its wattage. In tests published in February 2023, Consumer Product Safety Commission (CPSC) staff evaluated household heaters rated 2,000 watts or less. They included models rated 700 and 1,000 watts, and one advertised as 2,000 watts that drew a maximum of 1,500 watts. We use 1,500 watts on high and an assumed 750 watts on low as examples. Check your own heater’s label.
What It Costs at the U.S. Average Rate
Assumptions: U.S. average residential price of 18.16 cents per kWh for August 2026 (EIA Electricity Monthly Update, released Oct. 23, 2026); heater running continuously at the stated wattage; 30-day month.
| Setting | kWh per hour | Cost per hour | 8 hours a day for 30 days |
|---|---|---|---|
| High, 1,500 W | 1.5 | $0.27 | 360 kWh, about $65.38 |
| Low, 750 W | 0.75 | $0.14 | 180 kWh, about $32.69 |
The math for the high setting: 1.5 kWh × $0.1816 = $0.2724 an hour. Then 1.5 kWh × 8 hours × 30 days = 360 kWh, and 360 × $0.1816 = $65.38.
These are maximum figures. Most heaters have a thermostat that switches the element off once the room reaches the set temperature, so the real run time is often shorter than the hours the heater is turned on. A plug-in energy monitor will show your actual kWh.
What It Costs Where You Live
Rates vary widely by state, so the same heater costs very different amounts. These examples use EIA’s July 2026 state averages for residential customers (Electric Power Monthly, released Sept. 24, 2026), with the same 1,500 watts, 8 hours a day, 30 days.
| Example rate | Cents per kWh (July 2026) | Cost per hour | 360 kWh a month |
|---|---|---|---|
| Louisiana | 12.72 | $0.19 | $45.79 |
| North Carolina | 15.16 | $0.23 | $54.58 |
| U.S. average (August 2026) | 18.16 | $0.27 | $65.38 |
| Massachusetts | 30.49 | $0.46 | $109.76 |
The U.S. row uses August 2026 data and the state rows July 2026 data, so treat them as rough comparisons. Prices in winter can differ from summer. Your own bill shows your rate. Our guide to reading your electric bill shows where to find it. If your utility charges more in some hours, as on a time-of-use rate, running a heater in the evening peak can cost more than these averages.
When a Space Heater Saves Money
A space heater does not make heat more cheaply than other electric resistance heaters, such as baseboards. The Department of Energy (DOE) says electric resistance heating is “100% energy efficient in the sense that all the incoming electric energy is converted to heat.” Ceramic, oil-filled and infrared heaters of the same wattage use the same electricity.
Savings come from heating less space. In its discussion of baseboard heaters, DOE says zone heating, which warms only occupied rooms, “can produce energy savings of more than 20% compared to heating the whole area of your house.” That only works if you lower the main thermostat. If the furnace or heat pump keeps the whole house at the same temperature, the space heater’s cost is added on top.
DOE also notes that the rest of the house still needs enough heat to stay “well above freezing to avoid freezing pipes.”
Compared With a Heat Pump
If you heat with electricity, a heat pump is the efficient choice. DOE says heat pumps “easily cut electricity use by 50% when compared with electric resistance heating.” By that measure, heat a space heater delivers with 360 kWh would take roughly half, about 180 kWh, from a heat pump, about $33 at the U.S. average rate. Real savings vary with the heat pump and the weather.
If space heaters are carrying much of your winter heating, see our guides to choosing a heat pump and to this winter’s heating costs.
What About Solar?
Solar panels do little to offset a space heater. Heaters run most on winter evenings and nights, when panels produce little or nothing, and winter output is lower anyway (see how solar output changes in winter). Where exported solar is credited at less than the retail rate, the power for an evening heater is mostly bought from the grid at full price.
Use It Safely
CPSC estimates that portable heaters, including electric space heaters, were involved in an average of 1,600 fires a year from 2019 to 2021, with about 70 deaths and 160 injuries a year. CPSC advises:
- Keep heaters “at least three feet away” from drapes, furniture and bedding.
- Plug electric heaters “directly into a wall outlet,” never into an extension cord or power strip.
- “Never leave portable heaters turned on while sleeping.”
Sources and verification
| Important claim | Source | Status |
|---|---|---|
| U.S. residential average 18.16 cents/kWh, August 2026, released Oct. 23, 2026 | EIA Electricity Monthly Update | Verified |
| State averages, July 2026 (LA 12.72, NC 15.16, MA 30.49) | EIA Electric Power Monthly, Table 5.6.A, released Sept. 24, 2026 | Verified (from our stored EIA table) |
| Watt-hour definition | EIA, Measuring electricity | Verified |
| Heater ratings in CPSC tests (2,000 W or less; 700 W, 1,000 W; 1,500 W measured maximum) | CPSC Staff Assessment on Portable Electric Heaters, Feb. 2023 | Verified |
| Resistance heat 100% efficient; zone heating over 20% savings; heat pumps cut use by 50%; freezing pipes | DOE Energy Saver, Electric Resistance Heating | Verified |
| 1,600 fires, 70 deaths, 160 injuries a year (2019-2021); safety tips | CPSC, Jan. 22, 2025 | Verified |
| Cost calculations | Our math from the figures above | Verified (recomputed) |
Frequently asked questions
How much does a space heater cost per hour?
Multiply the heater's wattage by your electric rate. A 1,500-watt heater on high uses 1.5 kWh an hour, so at 18.16 cents per kWh (the U.S. residential average for August 2026) it costs about 27 cents an hour. On a 750-watt low setting, it is about 14 cents.
How much does it cost to run a space heater all month?
At 8 hours a day on high, a 1,500-watt heater uses 360 kWh in 30 days. That is about $65 at 18.16 cents per kWh. Running it 24 hours a day on high would triple that. A thermostat that cycles the heater off lowers the real cost.
Is a space heater cheaper than central heat?
It can be if you heat only one room and turn the central thermostat down. If the central system keeps running too, the heater adds to your bill. In discussing zone heating with baseboard heaters, the Department of Energy says heating only occupied rooms can save more than 20% compared with heating the whole house.
Are some space heaters more efficient than others?
Not much among resistance heaters. The Department of Energy says electric resistance heat converts all of the incoming electricity to heat. Oil-filled, ceramic and infrared heaters of the same wattage use the same electricity per hour. A heat pump is the efficient electric option.
Will solar panels cover a space heater?
Partly, at best. Space heaters run most on winter evenings and nights, when solar panels produce little or nothing. Under net metering rules that credit exports at less than retail, most of that power will be bought from the grid at the full rate.
