When the first real cold snap hits, a lot of people reach for a space heater instead of turning up the thermostat. It feels cheaper, and sometimes it is. But a space heater can also quietly add a surprising amount to your electric bill. Here’s how to figure out which option makes sense for you.
How much does a space heater cost to run?
Most plug-in space heaters use about 1,500 watts on high. To find the cost, divide the watts by 1,000 to get kilowatts, multiply by the hours you run it, then multiply by your electricity rate per kilowatt-hour (kWh).
For example, a 1,500-watt heater running 8 hours a day at 16 cents per kWh uses 12 kWh a day. That’s about $1.92 a day, or close to $58 over a month. Run it all day and night and the monthly cost can top $170. You can plug in your own numbers with our Space Heater Cost to Run Calculator.
Your real rate is on your electric bill. Divide the total charges by the kWh you used to get a true cost per kWh, since fees and taxes add to the base rate.
When a space heater saves money
A space heater makes the most sense when you only need to warm one small room for a few hours. A few common examples:
- Working from a home office while the rest of the house stays cooler
- Taking the chill off a bathroom or bedroom before bed
- Warming a room that doesn’t get enough heat from the furnace
In these cases you can turn the house thermostat down a few degrees and use the heater only where you are. That’s where the savings come from: heating less space, not heating more cheaply.
When the furnace is the better deal
Gas furnaces are usually much cheaper per unit of heat than electric resistance heat. If you try to heat several rooms, or the whole house, with space heaters, you’ll almost always pay more than you would with the furnace. Space heaters also struggle to keep up in drafty rooms on the coldest Minnesota nights.
If you heat with electric baseboard, the math is closer, because both options use electricity. In that case the savings again come from heating fewer rooms.
Ways to cut the cost either way
- Use the heater’s low or eco setting, which often draws around half the power.
- Pick a heater with a built-in thermostat so it cycles off once the room is warm.
- Close the door to the room you’re heating.
- Seal drafts around windows and doors with weatherstripping or plastic window film.
- Lower the furnace thermostat a few degrees at night or while you’re away.
Safety first
Space heaters cause a meaningful share of home heating fires. Keep them at least three feet from anything that can burn, including bedding, curtains and furniture. Plug them directly into a wall outlet, not an extension cord or power strip. Look for a model with tip-over protection and automatic shutoff, and never leave one running when you leave home or go to sleep.
Used carefully and in the right situation, a space heater can trim your winter bills. Used as a replacement for whole-house heat, it usually costs more.
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