Space heaters are one of the most misunderstood appliances in the American home. They feel cheap because they are small and inexpensive to buy, but they are among the most power-hungry devices you can plug into a standard outlet. If you have ever noticed your electric bill jump by $40 or $50 during a cold snap, a portable space heater running in the background is often the culprit. This guide breaks down exactly how much electricity a space heater uses, what it costs to run in 2026, and when a space heater actually saves you money versus when it quietly drains your budget.
The short answer: a standard 1,500-watt space heater uses 1.5 kilowatt-hours (kWh) of electricity for every hour it runs at full power. At the national average residential rate of 18.56 cents/kWh (March 2026), that works out to about 27.8 cents per hour, or roughly $6.68 per day if it runs continuously. Run that heater around the clock for a month and you are looking at close to $200 added to your bill for a single appliance.
The Simple Formula for Space Heater Cost
Every space heater has a wattage rating printed on a label near the power cord or on the bottom of the unit. Once you know the wattage, the math is straightforward:
Space Heater Cost Formula
Cost per hour = (Watts ÷ 1,000) × Electricity rate per kWh
Example: A 1,500-watt heater at 18.56¢/kWh:
(1,500 ÷ 1,000) × $0.1856 = $0.278 per hour
Want to test your own numbers? Use our Appliance Energy Usage Calculator to plug in your heater's wattage and your local rate.
The key insight is that almost every full-size electric space heater on the market draws either 1,500 watts on high or 750 watts on low. That is not a coincidence: a standard 120-volt household circuit safely delivers about 1,800 watts, and manufacturers cap heaters at 1,500 watts to leave headroom and prevent tripped breakers. So whether you buy a $25 ceramic heater or a $120 designer model, the electricity cost at full power is virtually identical.
Space Heater Running Cost Table (2026)
The table below shows what a 1,500-watt space heater costs at three common electricity rates: a low rate (12¢/kWh, typical of states like Washington or Idaho), the national average (18.56¢/kWh), and a high rate (32¢/kWh, typical of California or the Northeast).
| Run Time | @ 12¢/kWh | @ 18.56¢/kWh | @ 32¢/kWh |
|---|---|---|---|
| 1 hour | $0.18 | $0.28 | $0.48 |
| 8 hours (overnight) | $1.44 | $2.23 | $3.84 |
| 24 hours (all day) | $4.32 | $6.68 | $11.52 |
| 8 hrs/day × 30 days | $43.20 | $66.82 | $115.20 |
| 24 hrs/day × 30 days | $129.60 | $200.45 | $345.60 |
These numbers assume the heater runs at full 1,500-watt output the entire time. In practice, a heater with a thermostat cycles on and off to maintain a set temperature, so real-world costs are usually 40–70% of the figures above once the room reaches temperature. Still, the table shows why leaving a space heater running unattended is an expensive habit.
Do "Energy-Efficient" Space Heaters Actually Save Money?
This is where marketing gets slippery. You will see heaters advertised as "energy-saving," "eco," or "low-wattage infrared." Here is the physics that cuts through the hype: every electric resistance heater is 100% efficient. All of the electricity it consumes is converted into heat, with none wasted. A 1,500-watt ceramic heater and a 1,500-watt infrared heater produce exactly the same amount of heat and cost exactly the same to run.
What differs between models is how and where they deliver heat, which affects your comfort and how long the heater needs to run:
- Ceramic and fan-forced heaters warm the air quickly and are good for small enclosed rooms. The heat dissipates fast once they turn off.
- Infrared (radiant) heaters warm objects and people directly rather than the air. They feel effective in drafty or large spaces because you feel warm even if the air is cool, which can let you run them at lower output.
- Oil-filled radiators heat slowly but retain warmth after shutting off, so they cycle less and can be marginally cheaper over a long evening in a well-insulated room.
- Micathermic panels combine convection and radiant heat and warm a room evenly.
The only genuine way a space heater saves you money is through zone heating: turning down your central thermostat and heating only the room you are actually using. That brings us to the most important question.
When a Space Heater Saves Money (and When It Doesn't)
A space heater saves money only if it lets you lower your whole-home heating. If you drop your central furnace from 70°F to 62°F and use a single space heater to keep your home office comfortable during the workday, you can genuinely cut costs, because heating one 150-square-foot room is far cheaper than heating a 2,000-square-foot house.
However, if you run a space heater in addition to your normal central heating, or if you use several space heaters throughout the house, you will almost always spend more. Central heating systems, especially heat pumps, move heat far more efficiently than resistance heaters. A modern heat pump delivers 2–4 units of heat for every unit of electricity, while a space heater delivers exactly 1. If you want to see how those systems compare, read our guide on heat pump vs furnace running costs.
Rule of Thumb
One space heater + lowered central thermostat = savings.
Multiple space heaters, or a heater running alongside full central heat = higher bill.
Compare your winter heating scenarios with the Seasonal Electric Cost Calculator.
Seven Ways to Cut Your Space Heater Costs
- Use the built-in thermostat. A heater set to a target temperature cycles off once the room is warm, cutting runtime dramatically compared with running on constant high.
- Choose the right size. Match the heater to the room. A rule of thumb is 10 watts per square foot, so a 150-square-foot room needs about 1,500 watts, but a small 80-square-foot office is comfortable with a 750-watt setting.
- Close the door. Zone heating only works if the heat stays in the room. An open door lets warm air escape and forces the heater to run longer.
- Lower the central thermostat. Every degree you drop your whole-home setting for eight hours a day saves roughly 1% on heating costs.
- Use a timer or smart plug. Automatically shut the heater off overnight or when you leave a room so it never runs unattended.
- Seal drafts. Weatherstripping around windows and doors keeps the warm air in and lets the heater cycle off sooner.
- Never use an extension cord. A 1,500-watt heater draws 12.5 amps and can overheat a thin cord, which is both a fire hazard and a source of wasted energy. Plug it directly into a wall outlet.
Safety and Your Circuit
Because a 1,500-watt heater draws about 12.5 amps, it uses most of the capacity of a typical 15-amp household circuit. Running a heater and another high-draw appliance (a microwave, hair dryer, or second heater) on the same circuit can trip the breaker. According to the National Fire Protection Association, space heaters are involved in a large share of home heating fires, so always keep them at least three feet from furniture, curtains, and bedding, and buy models with tip-over and overheat auto-shutoff.
The Bottom Line
A 1,500-watt space heater costs about 28 cents an hour at the national average electricity rate, which adds up fast if you run it carelessly. Used strategically, however, it is a legitimate money-saver: heat only the room you occupy, turn down the central thermostat, and let the built-in thermostat and a timer control runtime. Before you rely on one all winter, calculate the real monthly impact with our Appliance Energy Usage Calculator and see how it fits into your overall monthly electric bill. For a broader seasonal plan, our winter bill-lowering guide covers every major heating cost in one place.
Key Takeaways
- A standard 1,500-watt space heater uses 1.5 kWh per hour, costing about 28 cents an hour at the national average rate and roughly $200 a month if run continuously.
- Every electric resistance heater is 100% efficient, so 'energy-saving' and infrared models cost exactly the same to run at the same wattage.
- A space heater only saves money when it lets you lower the central thermostat and heat a single occupied room (zone heating).
- Running multiple heaters, or one alongside full central heat, almost always increases your total bill.
- Use the built-in thermostat, a timer, and a closed door to minimize runtime, and never plug a heater into an extension cord.
- For whole-home heating, a heat pump is far cheaper per unit of heat than any resistance space heater.
Frequently Asked Questions
Is it cheaper to run a space heater or central heating?
It depends on how much space you heat. If you use one space heater to warm a single room while lowering your central thermostat, you can save money, because heating one small room is far cheaper than heating a whole house. But if you run a space heater alongside full central heating, or use several heaters at once, you will almost always spend more. Central systems, especially heat pumps, move heat far more efficiently than a resistance space heater, which produces exactly one unit of heat per unit of electricity.
How much does it cost to run a 1500-watt heater for 24 hours?
At the US national average rate of 18.56 cents per kWh, a 1,500-watt space heater running continuously for 24 hours uses 36 kWh and costs about $6.68 per day. Over a 30-day month of round-the-clock use, that is roughly $200. In practice, a heater with a thermostat cycles on and off once the room is warm, so real costs are usually 40 to 70 percent of that figure. Your local electricity rate is the biggest variable; the same heater costs about $4.32 a day at 12 cents and $11.52 a day at 32 cents.
Do infrared or 'energy-efficient' space heaters use less electricity?
No. Every electric resistance space heater is 100 percent efficient, so a 1,500-watt infrared heater and a 1,500-watt ceramic heater consume identical electricity and produce identical heat. Marketing terms like 'eco' or 'energy-saving' do not change the physics. What differs is how the heat is delivered: infrared heaters warm objects and people directly, which can feel effective in drafty rooms and may let you run them at a lower setting, but at the same wattage the cost is the same.
Can a space heater raise my electric bill a lot?
Yes, significantly. Space heaters are among the most power-hungry devices you can plug into a standard outlet. Running one 1,500-watt heater for eight hours a day for a month adds about $67 to your bill at the average rate, and continuous use can add $200 or more. This is why a single space heater left running is often the cause of an unexpected winter bill spike.
What size space heater do I need for a room?
A common rule of thumb is about 10 watts of heating per square foot of room space for a room with average insulation and ceiling height. That means a 150-square-foot room needs roughly a 1,500-watt heater, while a small 80-square-foot office is comfortable on a 750-watt setting. Choosing a heater that matches the room, and using its built-in thermostat, prevents wasting electricity by over-heating the space.
Are oil-filled radiators cheaper to run than ceramic heaters?
At the same wattage, no. Both are 100 percent efficient and cost the same per hour at full power. The practical difference is that an oil-filled radiator retains heat after the element shuts off, so in a well-insulated room it may cycle slightly less over a long evening, giving a small real-world saving. Ceramic and fan-forced heaters warm a room faster but lose that heat quickly once they turn off. Choose based on how you use the room, not on promised efficiency.
Is it safe to leave a space heater on overnight?
It is generally not recommended. Space heaters are involved in a large share of home heating fires, so leaving one running unattended, especially while you sleep, carries real risk. If you must use one overnight, choose a model with automatic tip-over and overheat shutoff, place it on a hard, flat surface at least three feet from bedding and furniture, plug it directly into a wall outlet, and use its thermostat and a timer to limit runtime and cost.