Space heater
How much electricity does a space heater use?
750–1,500 W · 12–25¢ per hour · $45–$185 per month at 8h/day
Every electric space heater converts essentially 100% of its input into heat. A $30 ceramic unit and a $300 designer tower with the same wattage produce the same heat for the same energy. The only variables that matter are wattage and how long you leave it on.
Why the bill jumps so fast
At 1,500 W, one hour is 1.5 kWh — about 25¢ at average US rates. Eight hours a day for a month is 360 kWh, roughly $59. Run two of them and you have added more to your bill than every other appliance in this section combined.
When a heat pump wins
Because a heater cannot exceed 100% efficiency, a heat pump at 250–350% efficiency delivers the same warmth for a third of the electricity. If you are heating a room every night, the payback on a mini-split is often one or two winters.
Cheap tactics that actually work
Lower the whole-house thermostat and heat only the room you are in. Put the heater on a timer or smart plug so it does not run while you sleep or while the room is empty. And plug it directly into a wall outlet — extension cords are a genuine fire risk at 1,500 W, not just an inconvenience.
Frequently asked questions
How many watts does a space heater use?
750–1,500 W. The figure on the rating label is the maximum draw; actual use varies with settings, age and usage pattern.
How much does it cost to run a space heater per month?
With the defaults above it comes to the monthly figure shown in the calculator. At 16.5¢/kWh — the US residential average — that is a realistic middle estimate. Your own bill may be 30% lower or higher depending on state.
Is it cheaper to run a space heater at night?
Only if your utility offers a time-of-use plan and you avoid the 4pm–9pm peak window. On a flat-rate plan, the time of day makes no difference to the total.
Does the calculator account for real-world duty cycles?
Not automatically — you enter the effective hours yourself. For compressing appliances like refrigerators and AC units, enter the running watts and roughly the proportion of time the compressor is on, which is usually 30–50%.
Will a newer space heater actually save money?
Compare the kWh figure in the calculator against an Energy Star model's stated annual use. If the difference is a few hundred kWh a year, the payback on a replacement is usually long; if it is over 500 kWh, it is worth pricing out.