Space Heater Cost to Run in 2026: Per Hour, Per Month, and When It Beats Central Heat

A space heater rated at 1,500 watts on its high setting uses 1.5 kilowatt-hours (kWh) for every hour its heating element is on. At the U.S. average residential electricity price for August 2026, 18.16 cents per kWh according to the EIA, that is about 27 cents an hour, $2.18 for an 8-hour stretch, and roughly $65 a month if the element runs 8 hours a day. In Nevada (12.72 cents) the same month costs about $46; in Hawaii (47.18 cents) about $170.

That covers the running cost. Whether a space heater saves money is a separate question, and the answer depends almost entirely on what heats the rest of your house. Against propane or heating oil, heating one room with electricity often wins. Against a 95% gas furnace at this winter's forecast prices, it wins only when the room you are heating needs less than about a quarter of the heat the whole house would. The arithmetic for both questions follows, using prices as of the EIA releases checked on October 28, 2026. More fuel-by-fuel comparisons are in our heating costs hub.

The arithmetic in one line

Cost = kilowatts × hours the element is on × price per kWh.

A 1,500-watt heater is 1.5 kilowatts. Many models also have a low setting at roughly half power; check the label on the back or bottom of the heater, which lists the wattage or the amps (watts = amps × volts, so a heater labelled 12.5 A at 120 V draws 1,500 W). Your price per kWh is on your electricity bill. Use the all-in figure: total electricity charges for the month divided by the kWh billed, which captures delivery charges and riders that the headline "energy rate" leaves out.

The low setting halves the cost per hour, but it also halves the heat. If the room needs 1,500 watts to stay comfortable, the low setting will run for twice as long, or simply fail to keep up, and the cost of the heat you actually receive does not change. Every resistance heater converts electricity directly into heat: one kWh in, 3,412 Btu of heat out, the conversion EIA uses for electricity. That is why the label on an oil-filled radiator, a ceramic heater, an infrared panel and a fan-forced coil heater all lead to the same running cost for the same heat output. They differ in how fast they warm you, how evenly they heat the room, how hot the surfaces get, and how quietly they run. They do not differ in efficiency.

What it costs in your state

The national average hides a fourfold spread. The table below uses EIA's August 2026 residential prices (preliminary, released in October 2026), which are the most recent state figures available when this page was checked. Prices on winter bills can differ from August prices, especially in states with seasonal rates.

Price changes over the past year matter too. Between August 2025 and August 2026, EIA's figures show the Hawaii average rising from 38.53 to 47.18 cents, Maine from 28.14 to 32.11 cents and Ohio from 17.55 to 19.38 cents, while Connecticut fell from 30.17 to 24.51 cents. A cost estimate built on an older rate of 15 or 16 cents per kWh understates the August 2026 U.S. average cost by 12% to 17% ((18.16 - 16) / 18.16 and (18.16 - 15) / 18.16).

Read the chart down a column for your price and across a row for your usage. The darkest cells are where a space heater stops being a small expense: in a high-price state, a heater whose element runs most of an evening adds well over $100 a month.

Why your heater probably uses less than the label suggests

The figures above assume the element is on for every hour counted. In practice, a heater with a built-in thermostat switches the element off once the room reaches its set point and back on as the room cools. The fraction of time it is on (its duty cycle) depends on how fast the room loses heat: outdoor temperature, insulation, window area, drafts, and how much colder the rest of the house is.

A heater warming a small, closed, interior room on a mild day might run only a fraction of each hour. The same heater in a drafty room with large windows on a cold evening may never cycle off at all, in which case it is undersized and the full 1.5 kWh per hour applies.

To know your heater's real consumption you have to measure it, and the safest way depends on the device. A plug-through energy meter reports cumulative kWh, but a heater runs near the limit of a standard plug and circuit, so use one only if both the meter's and the heater's manufacturers allow that use; never let a remote-switching smart plug turn a heater on unattended. Where that is not possible, the label wattage multiplied by a timed run is a good estimate for a heater that does not cycle, and smart-meter interval data (below) shows real use without touching the heater. Our guide to smart plugs and energy monitoring explains why generic smart plugs should not be used on heaters, and the kW vs kWh explainer clears up the units if your utility portal reports one and your heater label the other.

Utility interval data can also show it. On a smart-meter portal with hourly data, a space heater appears as a step of about 1.5 kW that switches on and off in a regular pattern during the hours it runs. If you see that step at night or in a room nobody is using, you have found both wasted money and a heater that is running unattended, which CPSC advises against.

When a space heater is cheaper than central heat

This question gets less attention than the hourly cost, and it has a clean answer once you put every heating source on the same footing: the cost of one unit of heat delivered into the house.

At EIA's U.S. average forecast prices for winter 2026-27, the cost per million Btu of delivered heat works out as follows (method and regional figures in our winter heating cost forecast by fuel):

The space heater column is resistance heat at the U.S. average forecast price of 18.23 cents per kWh: $53.43 per million Btu. The last column divides the whole-house cost by that figure. It answers this question: if you turn the central system down and heat only the room you are in, how small does that room's heat demand have to be, as a share of what the whole house would have needed, for the space heater plan to cost less?

Three readings come out of it.

In a gas-heated home, a space heater has to replace a lot of central heating to pay. Heat from a resistance heater costs about four times as much per unit as heat from a 95% gas furnace at these prices. The room you heat, plus the heat it leaks into the cooler rooms around it, must use less than about a quarter of what heating the whole house would. A single closed room in a large house can meet that. An open-plan living area usually cannot.

In a heat pump home, the bar is 33% to 40%. A heat pump's advantage over resistance heat is the same physics that makes it cheap to run. Turning it down and running a space heater only pays when the heated area is genuinely small. One special case: if your heat pump is relying on its backup resistance strips in very cold weather, it is temporarily no cheaper per unit of heat than a space heater, and zone heating loses nothing on those hours.

In a propane, oil or baseboard home, zone heating usually wins. Against oil at $5.26 a gallon, a resistance heater wins whenever the heated area needs less than about 84% of the whole-house heat. In homes heated by electric baseboards, a portable heater costs exactly the same per unit of heat as the baseboards, so the savings come entirely from heating less space, and the cheapest move is to turn down the baseboard thermostats in unused rooms rather than buy anything.

A worked example

Illustration with stated inputs. A household works from a closed 150-square-foot office in an 1,800-square-foot gas-heated house from 8 a.m. to 5 p.m. on weekdays. On a typical January day, keeping the whole house at 68°F during those nine hours takes the furnace an estimated 300,000 Btu of delivered heat. With the central thermostat set back to 60°F, the furnace delivers an estimated 200,000 Btu over the same hours, and the office heater runs at 1,500 watts for half of the nine hours.

The space heater plan saves 14 cents a day, about $3 over a month of workdays. That is a real but small saving, and it disappears if the setback saves less heat than assumed or if the heater runs more of the time. The same household with a propane furnace would save far more: the whole-house option costs 0.3 × $29.01 = $8.70, against 0.2 × $29.01 + $1.23 = $7.03 for the setback plan, a saving of $1.67 a day.

The two inputs that decide the result, the heat saved by the setback and the heater's real run time, are the ones worth measuring. A thermostat with runtime history shows the first; smart-meter interval data, or a meter both manufacturers approve for the heater, shows the second.

A second example: an evening in the den, heater off at bedtime

Illustration with stated inputs. A household with a heat pump (seasonal COP 2.5) spends 7 p.m. to 11 p.m. awake in a closed 140-square-foot den. Option one keeps the whole house at 68°F for those four hours. Option two sets the heat pump back to 62°F at 7 p.m. and runs a 750-watt heater in the den while people are in the room, with its own thermostat keeping the element on about 60% of the time. The heater is switched off at 11 p.m., before anyone goes to bed.

The saving is 21 cents an evening, about $6 over 30 evenings, and it depends entirely on the setback saving the assumed 25,000 Btu. Two cautions apply. DOE's Energy Saver guide advises against manually setting back a heat pump's thermostat if it causes the backup electric-resistance heating to come on, because that heat is more expensive; a smaller setback, or a thermostat suited to heat pumps, avoids spending the saving on resistance heat when the house recovers. And the heater goes off when the room empties: CPSC's January 2026 winter guidance says to turn off heaters when sleeping, and its February 2026 guidance says never to leave a portable heater running unattended in a confined space. A space heater is not a substitute for overnight heat in a bedroom.

What actually differs between heater types

If every resistance heater turns a kWh into the same heat, the choice between designs is about how that heat reaches you: a fan blowing air over an element, air rising past a hot surface, or a glowing element warming whatever faces it. That affects comfort, and comfort decides how long the heater runs and at what setting. For the bill, the useful heater is whichever one keeps you comfortable at the lowest setting for the fewest hours in your room; your smart-meter data will show which that is after a week of use. A label promising lower running cost than another resistance heater of the same wattage cannot be explained by the heater converting electricity more efficiently, only by it running less.

Where people lose money with space heaters

• Running a heater to fight a central system. If the space heater sits near the thermostat, it warms the sensor, the central system shuts off early, and the rest of the house gets colder while you pay resistance prices for the heat. Keep heaters away from thermostats.
• Heating a room with the door open. The room's heat demand then includes much of the house, which pushes the share above every break-even in the table except oil and baseboard.
• Heating an unused room to keep pipes from freezing. A 1,500-watt heater running around the clock for 90 winter days uses 3,240 kWh: about $588 at the August 2026 U.S. average price and about $1,529 at Hawaii's. For comparison, EIA forecasts that an average gas-heated household will spend about $640 on gas for the whole November-to-March season. It is also an unattended heater, which CPSC advises against: its guidance is never to leave a portable heater running unattended in a confined space and to turn off heaters when sleeping. The safer alternatives are pipe insulation, sealing the air leaks that chill the space and, where code allows, heat tape installed to the manufacturer's instructions, and keeping the home's central heat on a setting that protects the pipes. Our guide to cold floors and the insulation behind them covers where the cold comes from.
• Using the heater to cover for a fault. A room that is always cold can have a duct problem, a closed damper, a missing return path or an air leak. A heater treats the symptom at a high cost per unit of heat.
• Assuming a new heater is "more efficient." Marketing terms like "eco mode" usually mean a thermostat or timer that reduces run time. That can save money, but a heater cannot produce more heat per kWh than another resistance heater. A heat pump can, which is why a ductless mini-split is worth pricing for a room that needs extra heat every winter; see our mini-split installation cost guide.

The electrical side: why one heater per circuit

At 120 volts, 1,500 watts is 12.5 amps. That leaves almost no headroom on a 15-amp circuit: a heater that runs for hours is a continuous load, and the common electrical rule of thumb limits a continuous load to 80% of the breaker rating, 12 amps on a 15-amp circuit, which a 12.5-amp heater already exceeds. Keep it as the only load on that circuit; and a second 1,500-watt heater on that circuit would ask for 25 amps, more than the 15-amp breaker is rated for. Which outlets share a circuit varies house to house; the breaker labels, or an electrician, will tell you.

Practical rules that follow from the arithmetic:

• One heater per circuit, and nothing else heavy on that circuit while it runs.
• Plug it into a wall outlet directly. CPSC's guidance is to always use a wall outlet and never a power strip.
• If the plug or outlet feels hot, stop using that outlet and have it checked.

Safety, from the agencies that track the fires

The energy cost is the smaller risk. NFPA's home heating fire report, covering 2016 to 2020, found that U.S. fire departments responded to an estimated annual average of 44,210 home fires caused by heating equipment, which caused an estimated 480 civilian deaths a year. Space heaters accounted for about one-third of those fires but nearly nine out of ten of the deaths.

What follows summarizes agency guidance; it is general information, not professional electrical or fire-safety advice for your home. CPSC's winter guidance (February 19, 2026) sets out the basic rules:

• Keep all sides of the heater at least three feet from beds, clothes, curtains, papers, sofas and anything else that can burn.
• Always use a wall outlet, never a power strip, and never run the cord under rugs or carpeting.
• Place the heater on a stable, level surface where it will not be knocked over.
• Never leave a portable heater running unattended in a confined space.
• Turn off heaters when sleeping (CPSC, January 23, 2026).

Fuel-burning portable heaters (kerosene, propane) burn fuel indoors, which raises ventilation and carbon monoxide questions this cost page does not cover. If you use one, follow the manufacturer's instructions; CPSC's February 2026 guidance recommends CO alarms, and says interconnected alarms are best.

Choosing between a heater, a setback and a fix

The numbers above reduce to a short decision path:

1. Find your whole-house cost per unit of heat from your fuel and equipment (the table above, or your own rates).
2. Estimate the share of the house's heat that the occupied room needs, including leakage to cooler rooms. A closed, interior room in a large house is low; an open-plan space is high.
3. If the share is below the break-even for your fuel, a setback plus a space heater saves money. Check the heater's real use for a week in your smart-meter data to confirm.
4. If the room needs extra heat every winter for years, price a permanent fix: air sealing, a duct repair, or a ductless heat pump head, which DOE's Energy Saver guide says can provide up to three times more heat than the energy it uses.

Next up: if your heat comes from oil or propane and the break-even column made the case for zone heating, the bigger opportunity may be the whole system. Our heat pump vs gas furnace operating-cost method shows how to run the same per-unit-of-heat comparison for a full replacement, with your own rates in place of national averages.

Frequently Asked Questions

How much does it cost to run a 1,500-watt space heater for 24 hours?

If the element ran the whole time, it would use 36 kWh, which costs about $6.54 at the August 2026 U.S. average of 18.16 cents per kWh. That is a cost figure only: CPSC's guidance is to turn off heaters when sleeping and never to leave a portable heater running unattended in a confined space, so a space heater should not run around the clock.

Is it cheaper to use a space heater or turn up the heat?

It depends on your main heating fuel. At winter 2026-27 forecast prices, heat from a resistance space heater costs about four times as much per unit as heat from a 95% gas furnace, about 1.8 times as much as propane heat and about 1.2 times as much as heating oil heat. It saves money when the room you heat needs a small enough share of the whole house's heat: under roughly 26% against efficient gas, 54% against propane and 84% against oil.

Do oil-filled or infrared heaters use less electricity?

No. Every electric resistance heater turns each kWh into the same amount of heat, whatever its design. Oil-filled, ceramic, infrared and coil heaters differ in how quickly they warm you, how evenly they heat and how hot their surfaces get, not in efficiency. A heat pump, which moves heat instead of making it, can deliver more heat than the electricity it uses; DOE's Energy Saver guide puts it at up to three times more.

How much does a space heater add to a monthly electric bill?

At 8 hours a day for 30 days with the element on the whole time, a 1,500-watt heater adds 360 kWh: about $65 at the U.S. average price, $46 in Nevada and $170 in Hawaii, using August 2026 prices. Thermostat cycling usually brings the real figure down.

Can I plug a space heater into an extension cord or power strip?

CPSC's guidance is to always use a wall outlet and never a power strip, and to never run the heater's cord under rugs or carpeting. A 1,500-watt heater draws 12.5 amps at 120 volts, which is enough to overheat undersized cords and strips.

Is the low setting on a space heater cheaper?

Per hour, yes: a 750-watt setting uses half the electricity of 1,500 watts. But it also produces half the heat, so if the room needs the full output, the heater runs twice as long or the room stays colder. The cost per unit of heat is the same on either setting.