The Best Space Heaters

When it comes to testing space heaters, there are a few main questions: How safe is it? How loud is it? How quickly and evenly can it heat a room?

During intensive testing of dozens of space heaters, I lived for weeks in a home with its thermostat set to a chilly 65 degrees Fahrenheit.

I tested how well and quickly each device heated a medium-size room (14 by 14 feet), and also how well it heated a small seating area in a larger, open-format space. To test each heater's thermostat and also measure the evenness of heating, I placed thermometers at at least three locations in each room, including behind the heater.

I tested the loudness of each device with a decibel meter at 3 feet away and verified power usage with a wattmeter. To see whether the heater's exhaust put out painful levels of heat, I put my own fingers on the line.

Finally, I tested safety features and basic durability. I looked at independent safety certifications, of course. But I also rudely knocked over each device to verify how the device’s tip-over protections functioned, if at all, and verified that the device started working again when set back on its feet.

To test overheat protection, I smothered each device with an old sheet to see whether the device shut itself off or whether it adjusted its power output to keep internal temperature low.

If any device fails the tip-over or overheat tests, we don’t recommend it. If it’s significantly louder than 50 decibels at 3 feet, we don’t recommend it. If the heater breaks during routine operation, we don’t recommend it. Maddening rattles and squeaks are also disqualifying.

We keep on testing our favorites through the cold season and beyond, to see how they hold up over time. And, of course, we continually subject more heaters to our testing regimen to see if other devices can oust our current faves.

Basically all electric space heaters do the same thing: They take electricity off the grid, usually 1,500 watts of it, and turn that power into heat.

The vast majority of space heaters, including ceramic heaters and PTC heaters, are electric resistance heaters. This means they run an electrical current through something that creates resistance: maybe an electric coil or maybe a specially designed ceramic. This quickly turns electricity into heat.

Most space heaters use a fan to disperse this heat out into the world, where we all live. These forced-air convection heaters tend to be the fastest at quickly raising the temperature of the surrounding air. The air then heats you. And so while this variety heats quickly, it can take quite a bit of electricity to heat up a whole room.

Oil-filled radiators, in contrast, heat up oil that circulates inside the device, which then emits heat to the surrounding room. These tend to heat up slower but offer even and lasting heat and are quite quiet. These radiators operate on the same principle as steam radiators in buildings with a boiler room. And just like steam radiators, they can get really, really hot to the touch.

Radiant heaters, such as infrared heaters, operate much like the sun or a campfire: Rather than heat the air, they heat objects or people directly by radiating energy toward them. Infrared devices heat the air only indirectly, via the objects it heats— much the same way the sun's heat radiates off baking city streets. The glow is immediately palpable as warmth, but you’ll need to be in the path of the radiation to feel it, and the thermometer might not immediately register the warmth you perceive. Infrared heaters tend to be best at making an individual in front of the heater feel warmer without using a lot of energy.

Though they deliver heat differently, both infrared and oil-filled heaters are subject to the same wattage limitations, and have about the same efficiency, as electrical resistance heaters.

The same cannot be said for heat pumps, a newer technology that's expected to provide the next generation of household heat. Heat pumps don't use energy to create heat. Instead, they move heat energy from one place to another. Accordingly, they require far less energy than other forms of heater. But household systems cost thousands to install. And while more affordable window and portable heat pumps are ramping up, they're not yet broadly available.

Yes, but also definitely no.

Space heaters are much safer than they used to be. Modern space heaters are heavily regulated, especially regarding exposed heating elements and automatic shut-off switches to prevent overheating. But all heating devices require caution, and so do all devices that pull a lot of energy over long periods.

The vast majority of residential heating fires start with actual fire—specifically in fireplaces and fuel burners. But space heaters accounted for more than a thousand fires in the US each year from 2017 to 2019, according to the US Fire Administration. Though this accounted for just 3 percent of heating fires overall, these led to more than 40 percent of fatalities, in part because portable heaters tend to be placed precisely where people are and because the resulting fires are far more likely to be unconfined.

So treat your space heater with the caution and wild skepticism that it deserves. Here are some quite simple safety tips, courtesy of the fine federal experts at the USFA and the Consumer Product Safety Commission.

Don’t leave a space heater unattended. "Unattended” includes sleeping, y'all! If you insist on using one in your bedroom at night, get a device with a timed shut-off and use it, so it doesn’t run all night while you sleep. (Or, might we suggest a wonderful down comforter instead? So warmmmm.)

Plug your heater directly into the outlet. This is a big one. Do not, basically ever, use extension cords or power strips with space heaters. The added cord length builds up electrical load and can lead to shorts, overheating, and fires. If you must use a longer cord, consult an expert to ensure you get the proper gauge and rating.

Don’t plug another appliance into the same outlet or circuit as the space heater. Maybe the worst that happens is you trip the circuit breaker. But that’s not fun, either.

Place a space heater only on the floor, on a level surface. There’s no particular need to leave a space heater on a table or chair that might be unstable. Heat rises and travels around the room through convection.

Keep your heater at least 3 feet from flammable objects. This includes bedding, drapes, furniture, the dress you were going to wear, stray socks or stockings, your food delivery bag, and that great book you’ve been reading.

Don’t leave a portable heater running in a room with a baby, nor with a person who has mobility issues. The risk isn’t just fire but hyperthermia.

Keep space heaters away from water and even general dankness. Bathrooms are famously dangerous places for high-wattage electrical devices. But also: You know that damp basement? The one that's kinda cold and has puddles sometimes? Not a good place for a space heater.

Read the manual. Manufacturers have all kinds of good advice.

Nope! It may seem counterintuitive, but large heaters don't necessarily heat any better than small ones.

Whatever their physical size, most space heaters in the US and Canada deliver about the same amount of heat. Space heaters top out at 1,500 watts, which is the highest safe operating load for a 15-amp household circuit. And aside from some low-power personal heaters here and there, most space heaters you'll find on the market are 1,500-watt heaters.

What's more, electric space heaters are all pretty much 100 percent efficient in converting that electricity to heat. Whether directly or indirectly, nearly all of that energy will eventually become heat.

So if space heaters are the same power and the same efficiency, why are some 1,500-watt heaters advertised for small rooms and some for large rooms? This likely has as much to do with marketing as science. Pretty much every ceramic, electric-coil, or PTC heater has about the same amount of juice and thus the same ability to heat a room … at least eventually.

What differs among heaters is how and where the heat gets distributed and how fast. All other things being equal, the efficacy of a heater is mostly about whether it puts the heat where you want it to go.