How Much Does It Cost to Run a Space Heater?

By TrimWatt Editorial Team — who we areNot yet independently reviewed — how we reviewPublished July 22, 2026Figures last verified July 22, 2026

6 min read

QUICK ANSWER

Multiply the heater's wattage by hours used, divide by 1,000, and multiply by your electricity rate. A 1,500W heater run 8 hours a day costs 12 kWh a day — at 17¢/kWh that's roughly $2 a day, or about $60 a month.

A space heater is one of the few appliances where you can calculate the running cost exactly, because there's no efficiency rating to argue about: essentially all the electricity becomes heat.

The calculation

Watts ÷ 1,000 × hours = kWh. Multiply kWh by your rate. That's it.

Run time	Energy used	Cost
1 hour	1.5 kWh	≈ $0.26
8 hours/day	12 kWh	≈ $2.04/day
8 hours/day for 30 days	360 kWh	≈ $61/month

Worked example for a 1,500W heater at 17¢/kWh. Substitute your own rate from your bill.

The number that surprises people is the monthly one. A single heater in one room, run through an evening and overnight, can add more to a bill than most households expect from a device that plugs into a wall socket.

When a space heater actually saves money

There's exactly one scenario where it wins: you turn the central thermostat down meaningfully and heat only the room you're occupying. Zone heating like that can cost less than warming the whole house. Run the heater without touching the thermostat and you've simply added a 1,500W load.

Safety comes before savings

Space heaters are a recurring cause of home fires. Plug directly into a wall outlet — never an extension cord or power strip — keep three feet of clearance from anything flammable, and don't leave one running unattended or while asleep.

Same heater, same hours — four electricity rates

Same heater, same hours — four electricity rates. Values in $. Bars are proportional and start at zero; the exact value is given in the third column of each row.
12¢/kWh		$43
17¢/kWh		$61
22¢/kWh		$79
30¢/kWh		$108

One 1,500W heater run 8 hours a day for 30 days = 360 kWh. Monthly cost = 360 × your rate. Find your rate on your bill — it is the single biggest variable here. Arithmetic; rate range reflects the spread in EIA residential price data across U.S. states.

Will a space heater actually save you money?

1You lower the central thermostat and heat only the room you're in→ Yes, this is the one case where zone heating wins.

2You run it alongside unchanged central heating→ No. You've added a 1,500W load to your existing bill.

3You're heating a poorly insulated or draughty room→ Seal and insulate first — otherwise you're paying to heat the outdoors.

4You have a heat pump and use the heater to avoid backup heat→ Possibly, but check the arithmetic: resistance heat is resistance heat either way.

5You need it for one cold snap a year→ Running cost is irrelevant at that duration. Buy on safety features instead.

Where the numbers change

Your rate: a state at 12¢/kWh and one at 30¢+ produce completely different answers from identical use.
Thermostatic heaters cycle off once the room is warm, so real use is usually below the full-output figure.
Time-of-use plans can make evening running significantly more expensive than the average rate suggests.

What to do next

Take the wattage from the heater's label, your rate from the most recent bill, and run the arithmetic above for your real hours. If the monthly figure looks uncomfortable, the fix is usually better insulation or air sealing in that cold room rather than more heating.

What these numbers assume — and where they stop

Assumptions

A 1,500W electric resistance heater, the most common household size.
An electricity rate of 17¢/kWh in the worked example — check your own bill, U.S. rates vary widely by state.
The heater runs at full output for the hours shown; thermostatic models cycle and will use less.

Limitations

All electric resistance heaters convert essentially all their electricity to heat, so 'energy-efficient space heater' claims rarely mean lower running cost for the same output.
Whether a space heater saves money depends entirely on whether it lets you turn down central heat, not on the heater itself.
Rates vary enormously by state and by time-of-use plan; the example is arithmetic, not a prediction.

Sources

Space Heaters — U.S. Department of Energy — Energy Saver. Consulted July 22, 2026.
Electric Power Monthly (residential electricity prices) — U.S. Energy Information Administration. Consulted July 22, 2026.
Energy Saver: Save Energy, Save Money — U.S. Department of Energy. Consulted July 22, 2026.

Frequently asked questions

Are some space heaters cheaper to run than others?

At the same wattage and run time, no — electric resistance heaters are all roughly equally efficient at turning electricity into heat. Differences come from thermostats, timers, and how well the heat reaches you, not from the heating element.

Is a space heater cheaper than central heating?

Only if it lets you lower the central thermostat and heat one occupied room instead of the whole house. Running one alongside unchanged central heat simply adds cost.

Do infrared or 'eco' heaters use less electricity?

For the same wattage and run time they draw the same power. Infrared can feel warmer sooner because it heats objects and people directly, which may let you run it less — that's a usage saving, not an efficiency one.