How the cost is worked out
Electricity is sold by the kilowatt-hour, which is 1,000 watts running for one hour. So the cost of anything you plug in is:
watts ÷ 1,000 × hours × price per kWh = cost
A 1,500 watt heater uses 1.5 kWh every hour it runs flat out. The "share of that time" slider covers thermostats: a heater that cycles off half the time uses half the electricity, and the calculator multiplies by that share.
Electricity prices come from the U.S. Energy Information Administration's monthly table of average residential prices by state. The default is the US average for July 2026, 18.31 cents per kWh; your state's figure is on the picker, and the rate on your own bill beats both. The EIA table is a statewide average, so a utility in a big city or a rural co-op can sit well above or below it.
One thing the calculator takes for granted: every plug-in electric heater turns nearly all of its electricity into heat. The EIA's equipment review puts electric resistance heating at close to 100% because nothing goes up a flue (EIA, Residential Electric Resistance Furnaces, appendix B, page 25). That is why two 1,500 watt heaters cost the same to run whatever their shape or price tag.
Worked example
- 1,500 ÷ 1,000 = 1.5 kWh for every hour it runs.
- 1.5 kWh × 8 hours = 12 kWh a night.
- 12 kWh × $0.1831 = $2.20 a night.
- × 30 nights = $65.92 a month; × 4 months = $263.66 for the winter.
With a thermostat that keeps the heater off half the time, every figure halves: $1.10 a night, about $33 a month.
How many watts do heaters, fans and ACs use?
The presets on the calculator come from product labels and from figures our guides have already checked. Your own appliance's rating is printed on it, usually on a sticker at the back or on the plug.
| Appliance | Watts | Where the figure comes from |
|---|---|---|
| Full-size space heater on high | 1,500 W | The rating on the Pelonis and Lasko models in our electric vs oil-filled comparison; 1,500 W is the most a standard US outlet circuit allows a heater to draw |
| Oil-filled radiator on high | 1,500 W | Same rating, same heat: the oil-filled radiators we reviewed are 1,500 W models |
| Ceramic heater, 1,000 W model | 1,000 W | The 1,000 W PTC ceramic heater in which type of heater is cheapest to run |
| Personal or desk heater | 400 W | The 400 W models in space heaters that won't trip a breaker |
| Heat pump aux heat strips | 5,000 to 20,000 W | Electric heat kits are sold in 5, 8, 10, 15 and 20 kW sizes (MRCOOL universal heat kits); the preset uses 10 kW. The strips run on top of the heat pump itself |
| Window AC, 8,000 BTU | 660 W | The electrical rating of the LG LW8016ER, the first pick in our 8,000 BTU window AC guide (LG spec sheet). A more efficient unit draws less for the same cooling |
| Ceiling fan, 52 inch | 37 to 54 W | Hunter lists the energy use of its 52-inch fans between 37 W (Builder Elite) and 54 W (Outdoor Original); the preset uses 37 W. The light kit adds its own watts |
| Tower fan | 135 W | The figure in our guide to what a tower fan costs to run |
| Box fan | under 100 W | Our box fan guide; the preset uses 100 W |
| Electric blanket | about 100 W | Consumer Reports, citing the U.S. Department of Energy (a 2009 figure; blankets have not changed much since) |
Four ways to pay less
- Let the thermostat do the work. A heater that holds a set temperature cycles off once the room is warm, and the "share of that time" slider shows what that saves: at 60%, a $66 month becomes about $40.
- Heat the person, not the room. A 400 W desk heater or a 100 W electric blanket costs a fraction of a 1,500 W heater and is often enough at a desk or in bed.
- Do not pay extra for "efficiency" in a plug-in heater, because every 1,500 W heater makes the same heat. Pay for the features you will use, such as a thermostat, a timer or a quiet fan. Our energy-efficient space heater guide explains what efficiency means here.
- Check it against central heat. Running a space heater in one room is often cheaper than heating the whole house, and sometimes it is not. The heating cost by fuel tool puts your furnace or heat pump next to electric heat for your state.
Guides that go with this tool
- Electric heaters vs oil-filled heatersComparison
- Which type of heater is cheapest to run?Comparison
- 11 space heaters that won't trip breaker boxesBuying guide
- 12 energy-efficient space heatersBuying guide
- How much does it cost to run a tower fan?How-to
- 6 best 8,000 BTU window air conditionersBuying guide
FAQ
Does a 1,500 watt space heater cost the same to run whatever the brand?
Yes. Cost follows watts, not brand. Every plug-in electric heater turns nearly all of its electricity into heat, so two 1,500 watt heaters put out the same heat and cost the same per hour: about 27 cents at the US average rate of 18.31 cents per kWh (EIA, July 2026). A thermostat or a timer saves money only by switching the heater off sooner.
How much does it cost to run a space heater all night?
A 1,500 watt heater running for 8 hours uses 12 kWh. At the US average residential rate of 18.31 cents per kWh (EIA, July 2026) that is about $2.20 a night, or about $66 over 30 nights. If the heater has a thermostat and cycles off half the time, halve those figures.
Is an oil-filled heater cheaper to run than a ceramic or infrared heater?
Not at the same wattage. An oil-filled radiator rated 1,500 watts draws the same 1,500 watts as a ceramic or infrared heater on high. The oil holds heat after the element switches off, so an oil-filled model can cycle less often, but the electricity it turns into heat is the same.
Sources
- Electricity prices: EIA Electric Power Monthly, table 5.6.A, average residential price by state, July 2026 (released 24 September 2026).
- Electric resistance heat is close to 100% efficient: EIA, Updated Buildings Sector Appliance and Equipment Costs and Efficiencies, appendix B, Residential Electric Resistance Furnaces.
- Wattages: the product listings and guides linked in the table above; the LG LW8016ER spec sheet; Consumer Reports on electric blankets; MRCOOL heat kit sizes.
Prices last checked 20 October 2026. The calculator does not store anything you type.