Space heaters are the one appliance where the marketing and the physics openly disagree. Every electric resistance heater turns essentially all the electricity it draws into heat, so a 1,500 W ceramic tower, a 1,500 W oil-filled radiator and a 1,500 W infrared panel cost exactly the same per hour of running. What actually differs is how the heat reaches you, and therefore how long the thermostat keeps the element switched on.
A 1,500 W space heater draws 1.5 kWh for every hour it runs, which costs about [hed_cost appliance=”space-heater” period=”hour”] at the current US average of [hed_var key=”us_rate_cents” format=”cents”] per kWh. Six hours a day works out to [hed_cost appliance=”space-heater” period=”day”], or [hed_cost appliance=”space-heater” period=”month”] across a 30-day month. For context, the average US household electricity bill is about [hed_var key=”us_avg_bill” format=”money”] a month in total.
Why every 1,500 W heater costs the same to run
There is no such thing as a more efficient electric space heater. All of them are 100 percent efficient at converting electricity to heat, because heat is what electricity turns into when you make it fight through a resistive element. Claims that a particular heater will cut your bill in half are describing behaviour, not efficiency: you get a smaller bill if you heat one room instead of six, and that works with any heater.
So the wattage sticker is the whole story on cost. Most portable units are 1,500 W on high and 750 W on low, because 1,500 W is roughly the most you can pull from a standard 120 V outlet without tripping things. Larger 240 V garage and shop heaters go to 5,000 W and beyond, and they cost proportionally more.
[hed_wattage_matrix appliance=”space-heater”]Run time matters more than the setting
Here is where most cost estimates fall apart. A heater on a thermostat does not run continuously. Once the room reaches the setpoint the element switches off, and it only comes back on when the temperature drifts down. In a well-sealed bedroom the heater might run 20 minutes in every hour after the first half hour. In a drafty garage in February it might never switch off at all.
That means the honest way to estimate cost is to guess at running hours, not clock hours. If your heater is on from 6pm to midnight but the thermostat only calls for heat a third of that time, you are paying for two hours, not six. The table below assumes continuous running at each figure, so read it as the ceiling for that duration.
[hed_hours_matrix appliance=”space-heater”]Your electricity rate does more damage than your heater
The same heater costs four times as much in Hawaii as it does in Idaho, and nothing about the heater changed. If you only remember one thing from this page, make it this: find the cost per kWh on your electricity bill and use that number instead of any national average, including ours.
[hed_rate_matrix appliance=”space-heater”]Space heater running cost by state
Below is what a 1,500 W heater running six hours a day costs in every state, at current residential averages. Deregulated states are the ones where these figures move most, because your actual supply rate depends on the plan you are on rather than a single utility tariff.
[hed_state_costs appliance=”space-heater”]When a space heater is genuinely the cheaper choice
Space heaters get a bad reputation they only partly deserve. Running one costs roughly [hed_cost appliance=”space-heater” period=”hour”] an hour, which is expensive per unit of heat compared with a heat pump and usually more expensive than natural gas. But heating one occupied room at 1,500 W while letting the rest of the house sit at 60 degrees can genuinely beat running a central system at full setpoint, and that is the case where the maths works.
It stops working the moment you use two or three of them, or leave one running in an empty room, or use one as the primary heat source for a whole floor. At that point you are paying resistance-heating prices for a whole-house load, and a heat pump delivering three units of heat per unit of electricity will beat it comfortably. Our heat pump versus gas comparison covers that trade in detail.
Five changes that actually lower the number
The savings that actually move the number, roughly in order of how much they are worth:
- Use the low setting when it holds temperature. 750 W instead of 1,500 W halves the running cost to about [hed_cost appliance=”space-heater” watts=”750″ period=”hour”] an hour. In a small insulated room the low setting often keeps up fine once the room is warm.
- Turn the heater thermostat down, not the fan up. Every degree of setpoint you give back reduces how much of each hour the element runs.
- Put it on a plug-in timer or smart plug. The single biggest waste is a heater running in a room nobody is in, and a schedule fixes that without requiring discipline.
- Close the door and block the draft under it. Zone heating only saves money if the zone is actually sealed.
- Turn the central thermostat down at the same time. If you add a space heater without lowering the house setpoint, you have added a cost and removed nothing.
The circuit limit nobody reads until the breaker trips
A 1,500 W heater on 120 V draws about 12.5 amps. Standard household circuits are 15 or 20 amps, and continuous loads are supposed to sit at or below 80 percent of the breaker rating, which is 12 amps on a 15 A circuit. A single 1,500 W heater is therefore already at or slightly over the continuous-load limit for a 15 A circuit before anything else is plugged in.
In practice that means one heater per circuit, plugged directly into a wall outlet. Not an extension cord, not a power strip, and not sharing a bedroom circuit with a second heater. Space heaters are involved in a significant share of home heating fires every winter, and most of that is cord and outlet related rather than the heater itself failing. If you need to know what your circuit can carry, the watts, volts and amps calculator converts between the numbers on the label and the number on the breaker.
How this compares to everything else you plug in
Per hour of runtime, against the other things people use to stay warm. The mini-split figure is the interesting one: it moves heat rather than making it, which is why it does the same job for a fraction of the draw.
[hed_compare_table appliances=”space-heater,baseboard-heater,electric-fireplace,mini-split,electric-blanket,ceiling-fan”]Questions people actually ask
[hed_faq]Do space heaters use a lot of electricity?Yes, by household standards. At 1,500 W a space heater is among the largest single loads in a typical home, roughly equal to a dishwasher and about fifteen times a modern television. Running one six hours a day for a 30-day month adds around [hed_cost appliance=”space-heater” period=”month”] to the bill.
How much does it cost to run a space heater for 24 hours?A 1,500 W heater running continuously for 24 hours uses 36 kWh and costs [hed_cost appliance=”space-heater” hours=”24″ period=”day”] at the national average rate. Very few heaters actually run continuously, because the thermostat cycles the element on and off.
Are oil-filled radiators cheaper to run than fan heaters?Not per hour. A 1,500 W oil-filled radiator and a 1,500 W fan heater cost the same while running. The radiator holds heat in the oil and releases it slowly after the element switches off, so it may spend less of each hour drawing power in a room that holds heat well. That is a duty-cycle difference, not an efficiency difference.
Is a space heater cheaper than central heating?It depends on what you are replacing. Against electric resistance whole-home heating, using one space heater in one room is cheaper. Against natural gas central heating or a heat pump, a space heater is usually more expensive per unit of heat, and only wins if it lets you drop the whole-house setpoint substantially.
Does a space heater on low use half the electricity?Close to it. Most units switch between 1,500 W and 750 W, so the low setting draws about half, roughly [hed_cost appliance=”space-heater” watts=”750″ period=”hour”] an hour versus [hed_cost appliance=”space-heater” period=”hour”] on high.
Can I run two space heaters on the same circuit?No. One 1,500 W heater already draws about 12.5 amps, which is at the continuous-load limit for a 15-amp circuit. Two on the same circuit will trip the breaker at best, and overheat the wiring at worst.[/hed_faq]
Related running costs
[hed_related appliances=”baseboard-heater,electric-fireplace,garage-heater,electric-blanket,mini-split”]Running it on solar
A space heater uses [hed_daily_energy appliance=”space-heater”] a day, which needs about [hed_panels_needed appliance=”space-heater”] standard 400 W panels. Full array, battery and inverter sizing is on how many solar panels to run a space heater.
Run the numbers on your own bill
- Electricity Cost Calculator for your exact wattage and rate.
- Heat Pump vs Gas Heating Cost Calculator if you are weighing a permanent fix.
- Whole-Home Appliance Load Calculator to see where the heater sits against everything else.