How Much Does It Cost to Run a Space Heater?
Updated April 9, 2026
Just want the number? Use the energy cost calculator.
A 1,500 watt space heater costs about 25 cents per hour to run at the U.S. average electricity rate, which works out to roughly 2 dollars over an 8 hour evening and somewhere near 60 dollars a month if you run it that way most days. The exact number depends on your local rate and how many hours the heater actually stays on, but the math is simple once you have those two pieces.
The watts to dollars math
Electricity is billed by the kilowatt-hour, so the first step is turning watts into kWh.
- A space heater is almost always rated at 1,500 watts on its high setting, which is 1.5 kilowatts.
- Run it for one hour and it uses 1.5 kWh.
- The U.S. average residential rate is about 17 cents per kWh, according to the U.S. Energy Information Administration.
So 1.5 kWh times 17 cents is about 25.5 cents per hour. That single number is the key to everything else: multiply it by the hours you run the heater.
A few hours vs all day
Where people get surprised is the difference between running a heater for a short stretch and leaving it on.
- 4 hours an evening: about 1 dollar a day, roughly 30 dollars a month.
- 8 hours overnight: about 2 dollars a day, roughly 60 dollars a month.
- 24 hours straight: about 6 dollars a day, roughly 180 dollars a month.
The heater pulls the same 1,500 watts the whole time it is calling for heat, so the cost scales almost directly with hours. A thermostat or built-in timer helps, because once a room reaches temperature the heater cycles off and the running hours drop. If your rate is higher than the national average, scale every figure up. At 30 cents per kWh, that 8 hour night is closer to 3.60 dollars instead of 2.
When a space heater is the cheaper choice
A space heater makes financial sense when you are heating one room and would otherwise warm the whole house.
If you spend the evening in a single room, running a 1,500 watt heater there and turning the central thermostat down a few degrees can cost less than heating every room to the same temperature. The savings are biggest in a large or poorly insulated home where central heat works hard to reach far rooms you are not using.
When it costs more than central heat
The picture flips if you try to heat the whole house with space heaters.
Electric resistance heat, which is what nearly every plug-in space heater uses, converts electricity to warmth at about a one-to-one rate. A heat pump or an efficient gas furnace can deliver the same warmth for less money per unit of heat, so running several space heaters across a house usually costs more than the central system, not less. One or two heaters in the rooms you actually use is the sweet spot.
If you are weighing electric room heat against your furnace, it helps to know what the furnace itself draws and costs, which is covered in the furnace size calculator.
For a comparison with cooling costs, how much central air conditioning costs to run applies the same per-hour math to a 3 ton AC.
Find your own number
To price your own setup, you need the heater’s wattage (check the label, it is almost always 1,500), your hours per day, and your electricity rate from a recent bill. Drop those into the energy cost calculator and it returns the cost per hour, per day, and per month so you can compare it against turning the thermostat up instead.