Space heaters use more electricity than most household appliances, but less than you might think

A typical space heater draws between 750 and 1,500 watts while running. For comparison, a microwave uses about 1,000 watts, a hair dryer uses 1,500 watts, and a refrigerator uses 150 to 800 watts depending on the model. The difference is that your refrigerator runs intermittently throughout the day, while a space heater runs continuously whenever it is on.

If you run a 1,500-watt heater for eight hours a day, you use 12 kilowatt-hours (kWh) of electricity in that period. At the U.S. average rate of about 16 cents per kWh, that costs roughly $1.92 per day, or about $58 per month. A 750-watt heater at the same usage costs half that. The actual cost depends on your local electricity rate, which varies widely by region and utility company.

Space heaters are expensive to run because they convert nearly all their electrical input directly into heat. That efficiency is actually the problem — there is no waste to hide. A central heating system distributes warmth across your whole house, so the cost spreads across many rooms. A space heater concentrates that same energy in one small area, making the per-room cost much higher.

Key Takeaways

  • Space heaters draw 750 to 1,500 watts continuously, making them among the highest-power household appliances when running.
  • Running a 1,500-watt heater eight hours daily costs roughly $1.92 per day at average U.S. electricity rates, though your actual cost depends on your local rate.
  • Space heaters are most cost-effective when you heat only the room you are in rather than raising the temperature in your whole house.
  • Older heaters with manual thermostats waste more electricity than newer models with built-in temperature controls that cycle on and off automatically.

How space heater wattage translates to your electric bill

The wattage rating tells you how much power the heater draws at full strength. A 1,500-watt heater is the maximum allowed on a standard 15-amp household circuit in the United States — going higher risks overloading the circuit and tripping the breaker.

To estimate your monthly cost, multiply the wattage by the hours you run it per day, divide by 1,000 to get kilowatt-hours, then multiply by your electricity rate. If your utility bill shows you pay 18 cents per kWh and you run a 1,200-watt heater six hours daily, the math is: (1,200 × 6 ÷ 1,000) × 0.18 = $1.30 per day, or about $39 per month. Check your utility bill for your exact rate — it varies from about 10 cents per kWh in Louisiana to over 25 cents in Hawaii and parts of the Northeast.

Many heaters do not run at full wattage all the time. Models with a thermostat cycle on and off to maintain a target temperature. Once the room reaches the set temperature, the heater shuts off and uses zero watts until the temperature drops again. This cycling reduces average consumption, sometimes by 30 to 50 percent depending on how well your room holds heat.

When a space heater is cheaper than central heating

A space heater makes financial sense only when you heat a single room instead of your whole house. If you normally keep your home at 68 degrees but spend most of your time in one bedroom, turning down the central thermostat to 62 and using a space heater in that room can save money overall.

The break-even point depends on your home's size and insulation. A well-insulated 1,500-square-foot house with a modern furnace might cost $1 to $2 per hour to heat the whole space. A single bedroom might be 150 square feet — one-tenth of the house. If your central heating cost is $1.50 per hour, heating just that room with central heat costs about 15 cents per hour. A 1,500-watt space heater costs about 24 cents per hour at average rates. In this scenario, central heat is still cheaper, but the gap narrows if your furnace is old or your home is poorly insulated.

The real savings come from lowering the whole-house temperature while you use the heater. If you drop the central thermostat from 70 to 62 degrees, you reduce furnace runtime significantly. A 1,500-watt heater warming one room might then cost less than the furnace savings, especially in mild weather when the furnace would run less anyway.

Heater type and efficiency differences

Radiant heaters emit infrared heat that warms objects and people directly, similar to sunlight. They feel warm quickly but do not heat the air itself, so the room temperature may not rise much. They work well in drafty spaces or when you want warmth in one spot.

Convection heaters warm the air, which then circulates around the room. They take longer to feel warm but eventually raise the room temperature throughout. Most plug-in space heaters are convection models.

Oil-filled heaters are a type of convection heater that heats oil inside a sealed chamber, then radiates that warmth. They warm up slowly but retain heat longer after you turn them off, so they cycle less frequently and use slightly less electricity over time.

All space heaters convert electricity to heat at roughly the same efficiency — around 99 percent. The difference between models is not efficiency but features. A heater with a built-in thermostat and automatic shutoff uses less total electricity than one with a manual on-off switch, because it cycles on and off rather than running constantly. A heater with a timer or remote control does not use less power but makes it easier to turn off when you forget, which saves money in practice.

Safety limits on space heater power

Most household circuits in the United States are rated for 15 amps at 120 volts, which equals 1,800 watts maximum. In practice, you should not plug a space heater into a circuit that already has other devices running — a refrigerator, microwave, or other heater on the same circuit. A 1,500-watt heater plus a 500-watt device will trip a 15-amp breaker.

Some homes have 20-amp circuits in kitchens and laundry rooms, which can handle 2,400 watts. Even so, most space heaters max out at 1,500 watts because higher wattages become impractical for a single portable unit. A 240-volt heater can draw more power, but these are less common in residential settings and require a dedicated circuit.

Overloading a circuit is a fire hazard. If your breaker trips when you plug in a space heater, do not use an extension cord or power strip to work around it — that makes the problem worse. Instead, use a different circuit or choose a lower-wattage heater.

How to reduce space heater electricity use

Set the thermostat to the lowest temperature that feels comfortable. Each degree lower reduces runtime and cost. Many people find 68 degrees comfortable while sitting still and 70 degrees comfortable while active. Lowering the target by 2 degrees can cut usage by 10 to 15 percent.

Close doors to the room you are heating and seal obvious air leaks around windows and baseboards with weatherstripping or caulk. A room that holds heat longer requires less heater runtime. Closing vents in other rooms does not help — it just makes your furnace work harder if it is still running.

Use the heater only when you are in the room. A timer function helps if you forget to turn it off. Some newer models have occupancy sensors that shut off automatically when no motion is detected for a set period, though these are less common in budget models.

If you have an old heater with no thermostat, replacing it with a model that has automatic temperature control will reduce electricity use noticeably. The upfront cost is usually $30 to $100, but the savings add up quickly if you run the heater regularly.

Space heaters versus other heating options

A space heater is most cost-effective for supplemental heat in one room. If you need to heat your whole home, central heating, a heat pump, or a gas furnace is cheaper per square foot, even though the total bill is higher because you are heating more space.

A window air conditioner uses similar wattage to a space heater but runs only in summer. A portable air conditioner uses 3,000 to 4,500 watts and costs significantly more to run. A ceiling fan uses only 50 to 100 watts and does not heat at all — it circulates existing warm air, which can make a room feel warmer without raising the actual temperature.

If your goal is to save money on heating, the most effective steps are lowering your whole-house thermostat, improving insulation, sealing air leaks, and using a space heater only in the room where you spend the most time. A space heater alone, running constantly in an uninsulated room, will not save money compared to central heat.

Frequently Asked Questions

Will a space heater significantly increase my electric bill?

Yes, if you run it regularly. A 1,500-watt heater used eight hours daily adds roughly $50 to $60 per month to your bill at average U.S. rates. The impact is smaller if you use a lower-wattage model, run it fewer hours, or live in an area with cheap electricity. If you offset this by lowering your central thermostat, the net increase may be small or zero.

Is it cheaper to heat one room with a space heater or heat the whole house?

It depends on your home and heating system. If you lower your whole-house thermostat while using a space heater in one room, you usually save money. If you run the space heater while keeping central heat at normal temperature, you are paying for both and will see a higher bill. The break-even point varies by region and home size.

Can I use a space heater on an extension cord or power strip?

No. Space heaters draw high current and can overheat extension cords and power strips, creating a fire hazard. Always plug directly into a wall outlet. If the outlet is inconveniently located, move the heater or use a different heating method rather than using an extension cord.

Do newer space heaters use less electricity than older ones?

Not inherently — all space heaters convert electricity to heat at roughly the same efficiency. However, newer models often include thermostats and automatic shutoff features that cycle the heater on and off, reducing total usage. An old heater with a manual switch that runs constantly will use more electricity than a newer model with temperature control.

What is the cheapest way to use a space heater?

Use a lower-wattage model (750 watts instead of 1,500), run it only when you are in the room, set the thermostat as low as comfortable, and close doors to trap heat. Most importantly, lower your central thermostat while using the space heater so you are not paying to heat the whole house at the same time.