Space heater cost calculator

How much electricity does a space heater use?

A space heater uses its rated watts for every hour it is heating. A 1,500 W heater on high uses 1.5 kWh an hour; on low, at about 750 W, it uses 0.75 kWh.

Eight hours a day on high is 12 kWh a day and about 365 kWh a month. The average U.S. home uses about 863 kWh a month for everything, so one heater run like that adds more than 40% to a typical bill. At the U.S. average rate of 18.19¢ that is about $66.39 a month.

Do space heaters use a lot of electricity?

Yes, compared with almost anything else you plug in. A 1,500 W heater draws as much as 15 big-screen TVs or 150 LED bulbs, and it is one of the few appliances that runs at that level for hours at a time. A microwave or hair dryer draws the same power but only for minutes.

It is also as much as a normal outlet can supply. 1,500 W at 120 V is 12.5 amps, most of a 15 A circuit, which is why a second heater, or a heater and a vacuum, on the same circuit trips the breaker. Work out the amps for any appliance with the watts to amps calculator.

The thermostat changes the answer

The cost tables assume the heater runs flat out, which is what it does in a cold room it cannot keep up with. A heater with a thermostat switches off once the room is warm and back on as it cools, so it only draws power part of the time:

• Full power the whole time: a cold, draughty or large room, or a heater without a thermostat.
• About 75%: a cold room that the heater just about keeps warm.
• About 50%: a small, insulated room, or a mild day.

These are estimates. A plug-in power meter, about $20, records the kWh the heater really uses over a few days and settles it.

Which space heater is cheapest to run?

Per hour at the same setting, none of them. Every electric resistance heater, whether oil-filled, ceramic, infrared, quartz or sold as “eco”, turns 100% of the electricity it uses into heat, and a 1,500 W model uses 1,500 W. The differences are in how the heat arrives: infrared warms the person in front of it quickly, oil-filled radiators heat slowly and stay warm after they switch off, fans spread heat around the room. What saves money is a good thermostat, a lower setting, a smaller room and closed doors.

The only electric heating that is cheaper per unit of heat is a heat pump, including mini splits, which move heat rather than make it and deliver two to three times as much per kWh. Size one with the mini split size calculator.

Space heater or central heat?

A space heater saves money when it lets you turn the whole-house thermostat down and heat only the room you are in. It costs more when it is added on top of central heating, or used to heat a whole house, which is the most expensive way to heat a home with electricity.

Cost of a 1,500 W heater by state

At each state’s average residential rate, January to July 2026, running at full power.

Source: U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.B (preliminary). Averages before local taxes. For a list of appliances at once, use the electricity cost calculator.