A space heater looks like the most harmless thing in your house. It’s a little box that hums in the corner and keeps your feet warm.
It can also kill you.
The Consumer Product Safety Commission estimates portable heaters, electric space heaters included, are involved in roughly 1,600 fires a year. Those fires killed about 70 people and injured 150 annually, on average, from 2020 through 2022.
Here’s the number that really got my attention. The U.S. Fire Administration found that from 2017 through 2019, portable heaters started just 3% of home heating fires — yet they were involved in 41% of the fatal ones.
In other words, when a space heater fire happens, it’s far more likely to turn deadly. And the timing matters. The USFA found that January alone accounted for a quarter of portable heater fires in residential buildings.
Let’s talk about the six mistakes I see people make with these things. One can burn your house down. Another can add about $65 a month to your electric bill.
1. Plugging it into a power strip or extension cord
This is the big one, and plenty of us have done it.
A space heater on high draws a lot of power for hours at a time. Run it through a power strip or extension cord, and Maryland’s health department warns the strip or cord could overheat and start a fire.
The CPSC’s advice: Plug an electric space heater straight into a wall outlet, period. No power strip. No extension cord.
The U.S. Fire Administration goes a step further. Its heater safety card warns against running anything else on the same circuit as your heater, because that can cause overheating, too.
If the cord won’t reach where you want the heater, move the heater. And if you’ve got other hidden hazards around the house, here are seven fire hazards hiding in plain sight in your home.
2. Parking it too close to the couch, the curtains or the bed
Space heaters need at least 3 feet of room.
The CPSC says to keep portable heaters a minimum of 3 feet from anything that can burn: curtains, furniture, bedding and the like. That sounds obvious, but it’s exactly where people go wrong.
When the USFA dug into portable heater fires from 2017 through 2019, the leading contributing factor — 48% — was a heat source sitting too close to something combustible.
More of these fires started in bedrooms (34%) than in any other room. And in those bedroom fires, the thing most often ignited first was bedding — blankets, sheets and comforters — at 16%.
Picture that: a heater tucked beside the bed on a cold night, a comforter slipping off the edge. That’s how a lot of these fires start.
Set it on a solid, flat floor, measure out a 3-foot circle, and keep that zone empty. And don’t let kids or pets play near it.
3. Running it 8 hours a day without doing the math
Now let’s talk money, because a space heater can be a bigger bill than you think.
The U.S. Energy Information Administration says residential electricity averaged 18.19 cents per kilowatt-hour nationwide in 2026 through August. Here’s what that means for a 1,500-watt heater running on high for eight hours a day:
- 1.5 kilowatts x 8 hours = 12 kilowatt-hours a day
- 12 kilowatt-hours x 18.19 cents = about $2.18 a day
- Over 30 days, that’s about $65 a month
That’s roughly a nice dinner out for two, every month, for one appliance in one room. And your rate may be higher or lower than the national average, so plug in your own number from your bill.
The fix isn’t to freeze. It’s to run the heater less and smarter. Every hour a day you cut saves about $8 a month at that rate. And if your heater has a 750-watt low setting, using it cuts the cost roughly in half.
Quick aside — most internet financial advice comes from people who weren’t alive during the last recession. I’ve been writing about money for more than 35 years. Want rock-solid advice? Sign up for the free Money Talks Newsletter. Takes 10 seconds. No fluff. No spam.
4. Trying to heat the whole house with it
A space heater makes sense for one thing: warming the room you’re actually sitting in while the rest of the house stays cooler. Use it as a substitute for your furnace and the math turns ugly fast.
Run that same heater eight hours a day from November through March and you’ll spend about $330 — for one room.
Compare that to the EIA’s winter forecast. It expects the average home that heats with natural gas to spend about $640 for the November-to-March season, heating the entire house.
So two space heaters running eight hours a day all winter, at about $660, would cost more than the average gas-heated home is expected to spend keeping every room warm. That’s not saving money. That’s paying a premium to be less comfortable.
If your heating bill is the real problem, start with these simple ways to cut your home energy costs.
5. Leaving it running while you sleep or step out
This one’s simple, and it’s where good intentions go to die.
The CPSC says to switch heaters off before you go to sleep. The USFA says the same, and adds that you should turn a space heater off any time you leave the room.
Consumer Reports’ testers agree. “No space heater should ever be left unattended,” says Samantha Ostrander, who oversees the publication’s space heater tests.
I get the temptation. The bedroom’s cold, the heater’s cozy, and you’ll just doze off for a minute. But that’s precisely the setup in the bedding-and-bedroom numbers above. Warm the room before bed, then switch it off and use a heavier blanket.
A house fire is exactly the kind of disaster homeowners insurance exists for. If you haven’t reviewed your policy in a while, you can compare homeowners coverage here.
6. Buying one without tip-over and overheat shutoffs
The cheapest heater on the shelf isn’t a bargain if it’s missing basic safety features.
USFA’s checklist says your heater should shut itself off automatically if it tips over, and that an independent lab should have checked it for safety.
Consumer Reports adds that a sensor that kills the power when the heater overheats is a must-have. Look for a certification mark on the box or the heater itself, such as UL, Intertek’s ETL label or CSA Group.
If the heater you’ve been using for years has none of that, it’s time to retire it. A fire costs a lot more than a replacement.
Bottom line
A space heater is a tool, not a furnace, and it’s a tool that demands respect.
Plug it straight into the wall, give it 3 feet of empty space, turn it off when you leave or go to sleep, and make sure it shuts itself off if something goes wrong.
Then run the numbers on your own electric rate. At about $65 a month for eight hours a day, the cheapest heat is often the heat you don’t need — a sweater, a blanket, a closed door to the room you’re not using.
That’s the same lesson behind most household energy hogs. Your water heater can cost up to $600 a year, too, and a few small changes can shrink that bill.
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