How much does it cost to run a space heater?

By Nazrul Islam. Updated October 11, 2026.

Short answer: A standard 1,500-watt space heater on high uses 1.5 kWh every hour. At the U.S. Energy Information Administration's forecast 2026 average residential price of about 18 cents per kWh, that is about 27 cents an hour, $2.16 for an 8-hour day, and about $65 a month if it runs 8 hours every day. On a low setting of 750 to 900 watts, the cost drops to about half to 60% of that.

How to calculate space heater cost

Every electric space heater’s cost comes down to one line:

Cost = watts ÷ 1,000 × hours × your price per kWh

Watts are printed on the heater’s label. Your price per kWh is on your electric bill. If your bill lists several charges, divide the total amount by the total kWh used to get your real all-in rate.

Example: a 1,500 W heater running 8 hours at 18 cents per kWh uses 1.5 × 8 = 12 kWh, and 12 × $0.18 = $2.16.

Cost to run a 1,500-watt space heater

Almost every plug-in space heater sold in the U.S. tops out at 1,500 watts, the practical maximum for a standard 15-amp, 120-volt household circuit. These costs assume the heater runs on high the whole time:

Your electricity price	Per hour	8 hours a day	30 days, 8 hours a day
12¢ per kWh	$0.18	$1.44	$43.20
15¢ per kWh	$0.23	$1.80	$54.00
18¢ per kWh (about the 2026 U.S. average)	$0.27	$2.16	$64.80
25¢ per kWh	$0.38	$3.00	$90.00
30¢ per kWh	$0.45	$3.60	$108.00

The U.S. Energy Information Administration expects the average residential price to be about 18.2 cents per kWh in 2026. Prices vary a lot by state. Many states in the South, Plains and Mountain West pay around 13 to 16 cents, while New England, New York and California often pay close to 30 cents or more, and Hawaii roughly 50 cents. Use the rate on your own bill for the real number.

Running it 24 hours, and kWh per day

Use	Energy	Cost at 18¢ per kWh
1 hour on high	1.5 kWh	$0.27
8 hours a day	12 kWh a day	$2.16 a day
24 hours a day	36 kWh a day	$6.48 a day
8 hours a day for 30 days	360 kWh	$64.80 a month
24 hours a day for 30 days	1,080 kWh	$194.40 a month

For comparison, the average U.S. home used about 899 kWh of electricity a month in 2022, according to the EIA. One heater running nonstop can more than double a bill.

Cost of smaller heaters

Heater wattage	Per hour at 18¢	8 hours a day for 30 days
400 W (panel or desk heater)	$0.07	$17.28
750 W (typical low setting)	$0.14	$32.40
1,000 W	$0.18	$43.20
1,500 W (high)	$0.27	$64.80

Does a space heater run at full power all the time?

Not if it has a thermostat. The table above is the worst case. Three things bring the number down:

The thermostat cycles the heater. Once the room reaches the set temperature, the heater switches off and on to hold it. In a reasonably insulated room, it may draw full power only part of each hour. A heater that runs half the time costs half as much. Cheap heaters with only a high/low switch and no thermostat run at full power the whole time they are on.
The low setting uses less. Most heaters have a low setting of around 750 to 900 watts. Check your label or manual.
Eco modes cycle the heater more gently and avoid overheating the room.

A plug-in electricity monitor (the kind you plug the heater into) shows the actual kWh after a day or two. That is the most reliable way to know your real cost.

Are some space heaters cheaper to run?

Not per hour of heat. An electric resistance heater turns essentially all the electricity it uses into heat in the room. That is true for ceramic, oil-filled, infrared and fan heaters alike. A 1,500 W heater of any type uses 1,500 W and gives out about 5,100 BTU of heat per hour.

What differs is how the heat feels and how it is spread:

Ceramic and fan heaters heat the air quickly. Good for warming a small room fast.
Oil-filled radiators warm up slowly but stay warm after cycling off, so the room feels steadier.
Infrared heaters warm the people and objects in front of them, so you can feel warm sooner in a drafty space.

Be skeptical of any heater advertised as cutting your heating bill in half by itself. The only ways a space heater saves money are using it for fewer hours, at a lower setting, or instead of heating the whole house.

When a space heater saves money

A space heater saves money when it lets you turn down the heat for the rest of the house. This is called zone heating. If you spend the evening in one room, heating just that room with a space heater and lowering the central thermostat by 5 to 10 degrees can cost less than keeping the whole house warm.

It does not save money when the central heat stays at the same setting. Then the heater’s cost simply adds to your bill.

Compared with a heat pump, a space heater usually costs more per unit of heat. A heat pump moves heat from outdoors rather than making it, so it delivers about 2 to 4 units of heat for every unit of electricity in mild to cold weather, less in extreme cold. A resistance space heater delivers 1 unit for 1 unit.

What size space heater do you need?

A common rule of thumb for supplemental heating is about 10 watts per square foot. By that rule, a 1,500 W heater suits a room of up to about 150 square feet. Rooms with high ceilings, poor insulation, single-pane windows or an outside door need more, and a plug-in heater may not keep up in very cold weather.

Running a space heater on a portable power station

It drains the battery fast, and many smaller power stations cannot deliver 1,500 W at all. A 1,500 W heater uses 1,500 Wh every hour on high, so even a 2,000 Wh power station that can handle the load runs it for only about an hour once inverter losses are counted. In an outage, a heated blanket at around 100 W is a far better match for battery power. Try the numbers in our power station size calculator.

Safety: the rules that matter most

The National Fire Protection Association found that space heaters, including fuel-burning ones, were involved in 43% of U.S. home heating fires and 85% of home heating fire deaths from 2011 to 2015. Fire departments give the same core advice:

Keep the heater at least 3 feet away from anything that can burn: bedding, curtains, furniture, clothes and paper.
Plug it directly into a wall outlet. Do not use an extension cord or power strip, and do not run the cord under a rug.
Set it on a flat, hard, stable surface.
Turn it off when you leave the room or go to sleep.
If the plug, cord or outlet feels hot, unplug the heater and have the outlet checked by an electrician.
Choose a heater with tip-over and overheat shut-off, and a mark from a recognized testing lab such as UL, ETL or CSA.

Quick answers

How much does it cost to run a space heater all night? For 8 hours on high at 18 cents per kWh, about $2.16. If the thermostat keeps it running only half the time, about $1.08.

Is it safe to leave a space heater on overnight? Fire departments advise against it. Turn it off before you sleep, or use a heated blanket or mattress pad, which uses far less power.

How much does a space heater add to a monthly bill? Running one on high for 8 hours a day adds about $65 a month at the U.S. average price, or $43 to $108 depending on your rate.

Is it cheaper to run a space heater or the furnace? Heating one room with a space heater while you turn the furnace down is often cheaper. Heating the whole house with space heaters is usually more expensive than a gas furnace or a heat pump.