If you want the real number before you plug anything in, here it is: at the 2025 US average residential rate of 17.30 cents per kilowatt-hour, a space heater costs about 13 cents an hour on low and 26 cents an hour on high. The honest answer is still that no single figure fits everyone. Your rate, the wattage you actually use, and how long the thing runs all move that number a lot. What follows is the math, not a guess, so you can plug in your own bill and see where you land.
This post contains affiliate links. If you buy through them, we may earn a small commission at no extra cost to you. We only link to products we could verify exist.
The quick answer
A space heater is one of the most expensive things you can run in a house, watt for watt, because it turns electricity directly into heat with no efficiency tricks. At the 2025 US average residential rate of 17.30 cents per kilowatt-hour (per the U.S. Energy Information Administration), here is the honest range:
If this helped, you'll also want to read How Much Does It Cost to Leave a Fan On All Day?, Best Energy-Efficient Space Heaters Under $50 and Cheap Space Heaters for a Small Bedroom: Best Value Picks.
- A small 750-watt heater on low: about 13 cents an hour
- A typical 1,500-watt heater on high: about 26 cents an hour
- A big 1,500-watt unit running 8 hours a night: about $2.08 a day, or $62 a month
That last number is the one that surprises people. Run one heater high for a full winter and you can add $150 to $250 to your electric bill, and that's before you count the second heater in the bedroom.
How the number is built
The formula is not complicated, and you don't need a meter to use it. It goes like this:
watts multiplied by hours of use, divided by 1,000, then multiplied by your electricity rate per kilowatt-hour.
A 1,500-watt heater running for one hour uses 1.5 kilowatt-hours. Multiply that by your rate. If you pay 17 cents per kWh (close to the 2025 national average), that's about 26 cents. If you pay 30 cents, that's 45 cents. The heater is identical; the bill is not.
Two things trip people up. First, most heaters have a low and high setting, usually around 750 watts and 1,500 watts, so the "high" number is not the only number. Second, heaters cycle on and off once the room hits the set temperature, so a heater running for eight hours rarely draws full power for eight straight hours. Owner reviews and energy-monitor users consistently report that a well-sized heater in a small, closed room draws well under half its rated wattage over a full evening.
If you want to stop guessing, a plug-in meter like the P3 P4460 Kill A Watt EZ sits between the outlet and the heater and shows actual kilowatt-hours used. That turns the estimate into a real number for your house and your rate.
What pushes the cost up
Wattage is the biggest lever, and it's the one people ignore. A 1,500-watt heater costs roughly twice as much per hour as a 750-watt heater, full stop. There is no brand that changes that.
Running it longer than you need is the second. Heating an empty room, or heating a room with the door open to the rest of the house, means the heater never reaches its set point and never cycles down. It just runs flat out.
Cold rooms and bad insulation are the third. A heater working against a drafty window runs near-continuous. That's where cheap fixes pay for themselves fast. A 3M Indoor Shrink Film Kit or a Window Insulation Kit by Frost King costs a few dollars and can visibly cut how often the heater kicks back on, based on what owners report about drafty-room heating.
Finally, leaving a heater on all night at full blast is the single most expensive habit. Eight hours at 26 cents is about $2.08 a night, every night, all winter.
What brings the cost down
Use the lowest wattage that actually heats your space. A small, well-insulated bedroom often holds temperature fine on 750 watts, which halves the hourly cost.
Only heat the room you're in. This is the whole point of a space heater versus turning up the furnace, and it only works if you close the door.
Put the heat where you are, not where the ceiling is. Heaters with a fan move warm air around the room faster, so the thermostat set point is reached sooner and the unit cycles off. The Dreo Space Heater is a commonly recommended option in this category, and the Lasko 754200 Ceramic Heater is the budget standby that shows up in a huge number of owner reviews as a small-room workhorse. The Amazon Basics Ceramic Space Heater is another low-cost ceramic option if you just want something simple.
Control when it runs. A smart plug lets you schedule the heater to come on 20 minutes before you get up and shut off when you leave, instead of running all day. The Kasa Smart Plug HS103 and the Amazon Smart Plug both handle this and are widely used for exactly this purpose. Check the plug's wattage rating against your heater before you buy — most handle 1,500 watts, but confirm it.
Footprint and whether it fits a small space
This matters more than most buyers expect. A heater that's too big for the room gets shoved in a closet, and a heater that's too big for the shelf never gets used.
Floor footprint is the first constraint. A typical compact ceramic heater like the Lasko 754200 is roughly the size of a large coffee can and takes up maybe a 7-by-7-inch patch of floor. Tower-style heaters are taller but narrower, often under 8 inches wide. If your only free floor is a 10-inch strip beside a desk, measure before you buy.
Clearance is the second. Manufacturers typically specify 3 feet of clearance from furniture, curtains, and bedding. In a small bedroom, that rules out the corner behind the nightstand. Plan for open floor, not a gap.
Storage is the third, and it's the reason a lot of heaters die in a closet. If you only need heat for six weeks a year, a heater you can tuck on a shelf beats a bigger one that lives in the hallway tripping people. Compact ceramic units win here.
If you're heating a genuinely small space — a home office, a bathroom, a camper — a low-wattage ceramic heater is usually the right call. It won't heat a whole open-plan floor, and it isn't meant to.
Typical scenarios compared
| Scenario | Wattage | Hours/day | Approx. cost/hour* | Approx. cost/month* |
|---|---|---|---|---|
| Small bathroom, morning only | 750W | 1 | ~13¢ | ~$4 |
| Home office, workday | 1,500W | 6 | ~26¢ | ~$47 |
| Bedroom, overnight | 1,500W | 8 | ~26¢ | ~$62 |
| Whole evening, living room | 1,500W | 5 | ~26¢ | ~$39 |
| Two heaters, two rooms | 1,500W each | 6 each | ~52¢ | ~$94 |
*At the 2025 US average of 17.30 cents per kWh (EIA). Your rate will change these numbers, sometimes by double. Heaters that cycle off draw less than the full figure, so treat these as upper-end estimates.
The bottom line
A space heater costs real money to run — typically 13 to 26 cents an hour, and about $62 a month if you run one 1,500-watt unit 8 hours a night. It is not a cheap way to heat a house. It is a cheap way to heat one small room you're actually sitting in, and that distinction is the entire value proposition. Buy for the room you have, run it on the lowest setting that works, and put it on a schedule so it isn't heating an empty chair.
Three concrete ways to pay less: drop to the low wattage setting wherever it holds the room, seal the drafts around windows and doors so the heater cycles off sooner, and put the heater on a smart plug so it only runs when someone's there.
How these numbers were built
The electricity price used throughout is 17.30 cents per kilowatt-hour — the 2025 US average residential rate published by the U.S. Energy Information Administration in its Electric Power Monthly (Table 5.3). Every hourly figure is simple arithmetic on that rate: watts × hours ÷ 1,000 × price per kWh.
What is not verified here: your own rate, which varies by state and season (from roughly 11 to over 40 cents per kWh), and how much your heater cycles off once the room reaches its set temperature. The monthly figures assume full-wattage, full-hours use — a worst case, not a typical one. This article does not test heaters itself; it does the rate math and points you to a plug-in meter if you want your real number.
Frequently Asked Questions
How much does a 1,500-watt space heater cost per hour?
At the 2025 US average rate of 17.30 cents per kWh, about 26 cents an hour. If your rate is higher, it costs more; the wattage doesn't change, only your rate does.
Do space heaters actually cost less than heating the whole house?
Only if you're heating one small, closed room and leaving the rest of the house cooler. Run two or three heaters in different rooms and the cost climbs fast — two units at 1,500 watts each can run around $94 a month.
What's the cheapest way to cut space heater costs?
Use the lowest wattage that keeps the room comfortable, seal drafts with window insulation film so the heater cycles off sooner, and put it on a smart plug so it only runs when you're actually in the room.