Every winter the same question comes up: is it cheaper to plug in a space heater, or just turn up the thermostat? The honest answer is “it depends,” but on things you can actually work out. Here is the math, with real electricity prices, so you can decide for your own home.
What a space heater costs to run
Most plug-in space heaters draw up to 1,500 watts on high. That’s 1.5 kilowatts. To get the cost:
watts ÷ 1,000 × hours × your price per kWh
At 8 hours a day for 30 days, a 1,500-watt heater uses 1.5 × 8 × 30 = 360 kWh a month. Here’s what that costs at each state’s average residential price in EIA’s July 2026 data:
| State | Price per kWh | Per month (8 h/day) | Per hour |
|---|---|---|---|
| Louisiana | 12.72¢ | $45.79 | 19¢ |
| Florida | 15.03¢ | $54.11 | 23¢ |
| Texas | 15.88¢ | $57.17 | 24¢ |
| U.S. average | 18.31¢ | $65.92 | 27¢ |
| Ohio | 19.45¢ | $70.02 | 29¢ |
| New York | 29.90¢ | $107.64 | 45¢ |
| California | 33.61¢ | $121.00 | 50¢ |
| Hawaii | 48.00¢ | $172.80 | 72¢ |
Your own rate is on your bill (divide the electricity charges by the kWh used). Our utility cost calculator does the math for any appliance and any rate.
When a space heater saves money
A space heater is efficient at one thing: heating the room you’re in. Central heat warms the whole house, including rooms nobody is using. ENERGY STAR says that for the average American household, “almost half the annual energy bill goes to heating and cooling – more than $900 a year,” so it’s worth getting right.
A space heater tends to save money when:
- You spend most of the day in one room, like a home office, and can turn the central thermostat down for the rest of the house.
- You need a little extra warmth in one cold room and would otherwise crank the whole system up to fix it.
- Your electricity is relatively cheap compared with your heating fuel.
Example
Brian works from a spare bedroom in Columbus, Ohio. Instead of keeping the whole house at 70°F all day, he sets the thermostat to 64°F during work hours and runs a 1,500-watt heater on its thermostat setting in his office. At Ohio’s average 19.45¢ per kWh, even running on high for all 8 hours, the heater costs about $2.33 a day. Whether that beats heating the whole house depends on his furnace and gas price, which is why he compared two months of bills: one each way.
Low setting, lower cost
Many heaters have a 750-watt low setting. That halves the cost: 750 watts for 8 hours a day uses about 180 kWh a month, or about $33 at the U.S. average price. In a small, well-sealed room, low is often enough once the room has warmed up. A heater with a built-in thermostat cycles on and off by itself and usually costs less than the “on high all day” figures in the table.
A simple way to compare with your furnace
You can’t compare a space heater with central heat without your own numbers, because furnaces, fuels and homes differ so much. But the logic is simple. Look at what heating cost you last January (the gas or electric part of the bill above your summer baseline). If turning the thermostat down by several degrees saves more per month than the space heater costs to run, the heater wins. If the savings are smaller, it doesn’t.
Example: hypothetical numbers
Say Ashley’s winter heating costs her about $140 a month above her summer bill. She tries keeping the thermostat lower during the day and running a heater on low in her office. If her heating portion drops to $110 and the heater adds $33 in electricity, she’s $3 worse off, and should go back to the old way. If her heating drops to $90, she’s $17 ahead. The only way to know is to test it.
When it costs you more
- You use it on top of the central heat without turning the thermostat down. Then it’s pure extra cost.
- You run several at once. Three heaters on high cost three times as much, and at that point you’re heating the house the expensive way.
- You have an efficient heat pump. Heat pumps move heat instead of making it, so they can deliver more heat per kWh than a resistance space heater. Turning one down to run a space heater may not save anything.
- Your electricity is expensive. In states with high rates, like California or Hawaii, the math tilts away from plug-in heaters quickly.
Types of space heaters
- Ceramic fan heaters warm a room quickly and are common and inexpensive. Good for short bursts.
- Oil-filled radiators heat up slowly but hold heat and stay quiet. Good for a bedroom or office used for hours.
- Infrared heaters warm people and objects in front of them rather than the air. Good when you sit in one spot.
Here’s the part marketing doesn’t mention: nearly all plug-in electric resistance heaters turn electricity into heat at about the same efficiency. A 1,500-watt heater produces about the same amount of heat whatever its shape or price. Paying more gets you features like a thermostat, quieter operation or better safety, not more heat per dollar of electricity.
Cheaper ways to feel warmer
- Seal drafts around doors and windows with weatherstripping or a door snake.
- Use curtains: open on sunny days to let heat in, closed at night to keep it.
- Put down a rug on bare floors.
- Use an electric blanket or heated throw. They use far less power than a space heater; check the wattage on the label.
- Dress for the house you want to heat. A sweater and warm socks let you set the thermostat a couple of degrees lower without noticing.
How to test it in your own home
The most reliable answer comes from your own bills. Try one month with your usual thermostat setting and one month with the thermostat lower plus a space heater in the room you use. Compare total heating costs (electric and gas, if you have both), adjusting for how cold each month was. Many utilities show “heating degree days” or average temperature on the bill to make that comparison fair.
Run it safely
- Plug it straight into a wall outlet, not an extension cord or power strip.
- Keep at least 3 feet clear around it: no bedding, curtains, papers or furniture.
- Choose one with tip-over and overheat shut-off.
- Turn it off when you leave the room or go to sleep.
- Never use a stove or oven to heat your home.
If your winter bills are a shock every year, our guide on why your electric bill is high walks through the other common causes. And for live rates in your state, see our electricity cost pages.
