How much does it cost to run a space heater for 8 hours?

A 1,500-watt heater running 8 hours uses 12 kWh, which costs $2.18 a day at 18.16 cents per kWh, $15.25 a week, $66.10 a month, and $793.23 a year. At 4 hours a day it costs $33.05 a month. Running it 24 hours a day costs $6.54 a day and $198.31 a month.

Is a ceramic heater cheaper to run than an oil-filled radiator?

No. All resistive electric heaters convert electricity to heat at 100 percent efficiency, so a 1,500-watt heater of any type costs the same $0.27 an hour. The differences are in how the heat is distributed and how long it lingers, not in how much it costs.

Can I leave a space heater on overnight?

No. Never leave a space heater running unattended, and never leave it running while you sleep. Keep it three feet from anything that can burn, and plug it directly into the wall, never into an extension cord or a power strip, because it draws 12.5 amps on a 15-amp circuit.

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The current ledger · Table No. 47

How Much Does a Space Heater Cost to Run?

A 1,500-watt space heater running 8 hours a day costs $66.10 a month at the national average rate, $171.74 in Hawaii, and $46.30 in Nevada. This article prices it by the hour, the thermostat, and the state, and states why the heater type does not matter.

Filed November 4, 2026 · figures checked against 2026 sources

The short answer

A 1,500-watt space heater running 8 hours a day costs $66.10 a month at the national average rate of 18.16 cents per kilowatt-hour, and $793.23 a year if it ran every day, which it does not, because November is the month the heaters come out and March is the month they go back, and the heating season is about five months, so the season costs about $330.51 at 8 hours a day, which is the number to budget, not the year. The heater uses 1.5 kilowatt-hours an hour, which is $0.27 an hour, and 12 kilowatt-hours a day, which is $2.18 a day, and 84 kilowatt-hours a week, which is $15.25 a week, and the arithmetic is the whole story, because the heater is the simplest appliance in the house: it is a resistor, it draws its rated watts while the element is on, and it costs the watts times the hours times the rate, with nothing hidden. The rate is the U.S. Energy Information Administration's August 2026 residential average, 18.16 cents, and the state you live in moves the number more than anything you do with the heater: the same heater costs $171.74 a month in Hawaii, $116.88 in Maine, $108.29 in California, $104.29 in New York, $57.91 in Texas, and $46.30 in Nevada, which is 3.71 times less for the identical heater and the identical hours.

The heater is the appliance people ask about most in November, because it is the appliance that appears in November, and the question is always the same, how much will it add to the bill, and the answer is always the same shape, $0.27 an hour, and the hours are the answer, because the watts are fixed at 1,500 and the rate is fixed by the state, and the only number the household controls is the hours, and the hours are the thermostat, and the thermostat is the savings. Four hours a day instead of eight cuts the cost from $66.10 a month to $33.05, which is $396.61 a year saved, and the heater on its low setting, 750 watts, costs half the high setting at the same hours, which is $33.05 a month at 8 hours, and the heater that runs all night, 24 hours, costs $6.54 a day and $198.31 a month, which is the number that surprises people, because $0.27 an hour sounds like nothing and $198.31 a month sounds like a bill, and both are the same heater.

Hours per day	kWh per day	Cost per day	Cost per month	Cost per year
2 hours	3	$0.54	$16.53	$198.31
4 hours	6	$1.09	$33.05	$396.61
8 hours	12	$2.18	$66.10	$793.23
12 hours	18	$3.27	$99.15	$1,189.84
24 hours	36	$6.54	$198.31	$2,379.68

The table is priced at 18.16 cents, 7 days a week, a month of 52 divided by 12 weeks, and it is linear, because the heater is linear: double the hours and the cost doubles, halve them and it halves, and the only nonlinearity is the thermostat, which is the next section. The 24-hour row is the number to remember when the heater is left on overnight, because $6.54 a day is the cost of forgetting, and the heater that runs all winter, 24 hours a day for five months, costs about $991.54, which is the price of a holiday, and which is why the thermostat matters more than the heater.

The thermostat is the savings

A space heater with a thermostat does not draw 1,500 watts for every hour it is plugged in. It draws 1,500 watts while the element is on, and nothing while the element is off, and the thermostat cycles it, so a heater plugged in for 8 hours may have its element on for 5, and the cost is the element-on hours, not the plugged-in hours, which is why the calculator asks for the hours it runs, not the hours it is on. The room, the insulation, the outside temperature, and the thermostat setting decide the duty cycle, and the duty cycle decides the bill: a well-insulated room at 68 degrees may cycle the heater half the time, which halves the cost from $66.10 to about $33.05 a month, and a drafty room at 75 degrees may cycle it nearly always, which is the full $66.10, and the difference is the house, not the heater. The practical way to measure the duty cycle is a smart plug with energy monitoring, which records the actual kilowatt-hours over a week, and which typically costs $15 to $25, and which pays for itself the first time it shows a heater running 8 hours a day when the household thought it ran 4, because the measurement is the truth and the guess is the bill.

The heater's type does not change the cost, which is the fact most heater marketing hides. A ceramic heater, an oil-filled radiator, a fan heater, and an infrared panel all convert electricity to heat at 100 percent efficiency, because resistive electric heat has nowhere else for the energy to go, and a 1,500-watt heater of any type produces the same heat per kilowatt-hour, and costs the same $0.27 an hour, and the differences are in how the heat is distributed and how long it lingers, not in how much it costs. The oil-filled radiator keeps radiating after the element switches off, which feels more even, and the fan heater warms the air fast, which feels quicker, and the ceramic heater is lighter, which is easier to move, and none of them is cheaper per unit of heat, because the physics does not allow it, and the heater that claims to heat a room for pennies is claiming to break the first law of thermodynamics, and the claim is the marketing, and the $0.27 an hour is the physics.

Heater against central heat

The question behind the question is whether the space heater is cheaper than turning up the central heat, and the answer depends on what the central heat burns and how much of the house needs warming. Heating one room with a space heater and letting the rest of the house run cooler is usually cheaper than heating the whole house to the same temperature, because the house is larger than the room, and the heater warms the room the person is in, and the central system warms the rooms the person is not in, which is the waste. Heating the whole house with space heaters is almost always more expensive than the central system, because the central system is one heater for the whole house, and the space heaters are one heater per room, and the house has more rooms than the person has heaters, and the electricity is priced per kilowatt-hour while the gas is priced per therm, and gas is usually cheaper per unit of heat, which is why a gas furnace heats a house for less than electric heaters do, and why the space heater is the supplement, not the system.

The comparison to run is the room against the house: if the central heat is gas, and the household is one person in one room for the evening, the space heater at $0.27 an hour is cheaper than raising the whole house by three degrees, because the furnace would burn gas to warm every room, and the heater burns electricity to warm one, and the one room wins. If the central heat is electric baseboard, the comparison is closer, because the baseboard is also resistive electric heat at 100 percent efficiency, and the space heater is the same physics in a smaller box, and the difference is only the rooms warmed, and the space heater wins when the rooms warmed are fewer. If the household is the whole family, spread across the house, the central system wins, because the space heaters multiply, and four heaters at $0.27 an hour are $1.09 an hour, which is $26.15 a day, which is more than the furnace, and the rule is simple: one room, one heater; the whole house, the central system; and the thermostat is the savings in either case.

The new insight

The space heater is the only appliance in the house whose cost is exactly proportional to the hours, and whose hours are exactly proportional to the thermostat, which makes it the only appliance where the savings are entirely in the household's hands. The watts are fixed at 1,500, because that is the most a standard 120-volt outlet safely delivers, and the rate is fixed by the state, because the household does not set it, and the hours are the thermostat, and the thermostat is the household, and cutting the hours from 8 to 4 saves $33.05 a month and $396.61 a year, which is the cheapest efficiency measure there is, because it costs nothing, and it starts tonight, and it is the only appliance where the advice is not to buy a better one, but to run the one you have for fewer hours, because the heater is already 100 percent efficient, and the only inefficiency is the hours, and the hours are the choice.

How to run it cheaper, and how to run it safely

The cheaper ways are the hours, the setting, and the room. Run it 4 hours instead of 8, which saves $33.05 a month. Run it on low, 750 watts, which halves the cost at the same hours, to $33.05 a month at 8 hours. Heat the room you are in, and let the rest of the house run cooler, which is the one-room rule, and which is the reason the heater exists. Close the door, because the heater warms the air, and the air leaves through the open door, and the thermostat cycles more, and the bill rises, and the door is free. Put it where the heat stays, away from the draft, and away from the window, because the window is the coldest surface in the room, and the heater beside it warms the glass, and the glass warms the outside, and the outside is not the room. Measure it with a smart plug for a week, because the measurement is the truth, and the truth is usually that the heater runs longer than the household thinks, and the plug is $15 to $25, and it pays for itself the first time it shows the real hours.

The safety rules are the ones that matter more than the money, because a space heater is a 1,500-watt resistor in a room full of fabric, and the rules are simple: keep it three feet from anything that can burn, including bedding, curtains, and furniture, and never leave it running unattended, and never leave it running while you sleep, and never plug it into an extension cord or a power strip, because the heater draws 12.5 amps on a 15-amp circuit, and the extension cord is the weak point, and the weak point is the fire, and the outlet is the place it belongs, directly, with nothing between it and the wall. A 1,500-watt heater is the maximum a standard outlet safely delivers, which is why every space heater tops out at 1,500 watts, and why the heater that claims 1,800 watts is claiming to exceed the circuit, and the circuit is the limit, and the limit is the safety.

Sources

U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A, August 2026: U.S. residential average 18.16 cents per kWh; state rates Hawaii 47.18 cents, Maine 32.11, California 29.75, New York 28.65, Texas 15.91, Louisiana 12.87, Nevada 12.72. Smart plug pricing: energy-monitoring plugs from Kasa, Emporia, and Shelly typically $15 to $25. Heater physics: resistive electric heat converts electricity to heat at 100 percent efficiency; a 1,500-watt heater on a standard 120-volt, 15-amp circuit draws 12.5 amps, which is the practical maximum for a plug-in heater. All calculator figures were computed by this site's calculator under the stated model: kWh per day is watts times hours divided by 1,000; a month is the weekly figure times 52 divided by 12; cost is kWh times the rate.