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Space Heater Cost Calculator

Find what an electric space heater costs per hour and per month, including thermostat cycling.

Quick answer

A 1,500 W space heater costs about 26¢ an hour at full power and $0.17/kWh. Run 5 hours a day with the thermostat cycling 80% of the time, that is about $1.02 a day or $31 a month. Cooling instead? See the AC cost calculator.

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  • Energy
  • Updated October 2026
W

On the label or manual. 1 kW = 1000 W.

%

Share of time it actually draws full power. AC and fridges cycle on and off; lights and TVs are 100%.

Find it on your bill (cents ÷ 100).

Cost per month (30 days)

$30.60

Cost per day
$1.02
Cost per year
$372.30
Cost per hour of use
$0.20
Energy per day
6 kWh
Energy per month
180 kWh
Show the working
  1. 1,500 W × 5 h × 80% × 1 ÷ 1000 = 6 kWh/day
  2. 6 kWh × $0.17 = $1.02 per day

About the Space Heater Cost calculator

Most plug-in heaters in North America max out at 1,500 W because that is the limit for a standard 15 A outlet; many have a 750 W low setting. In the UK and Europe, 2,000–3,000 W heaters are common.

All resistive electric heaters — fan, oil-filled, ceramic, infrared — turn electricity into heat at essentially 100% efficiency. What differs is how they deliver it. A thermostat will cycle the heater off once the room is warm, which is why the default load is 80%.

Heating one small room with a space heater can be cheaper than running central heat for the whole house. Heating a large, drafty room with one usually is not.

How to use it

  1. Enter the heater wattage (setting you actually use).
  2. Enter the hours per day.
  3. Lower the load if the thermostat clicks off often.
  4. Enter your electricity price.

The formula

Cost per hour = Watts × Load ÷ 1000 × Price

  • A 1,500 W heater at full power uses 1.5 kWh every hour.

Worked example

A 1,500 W heater for 5 hours

  1. 1,500 × 5 × 0.8 = 6 kWh per day.
  2. At $0.17/kWh: $1.02 per day.
  3. About $30.60 per month.

Frequently asked questions

Are oil-filled radiators cheaper to run than fan heaters?

Per kWh, no — every electric resistance heater is equally efficient. Oil-filled units release heat more gently and keep radiating after switching off, which can feel more comfortable and cycle less often.

Is a heat pump cheaper than a space heater?

Yes, usually much cheaper. Heat pumps deliver 2–4 units of heat per unit of electricity, compared with 1 for a resistive heater.

How much does it cost to run a heater overnight?

Enter 8 hours. A 1,500 W heater at 60–80% load uses roughly 7–10 kWh overnight.

Results are estimates for planning — check critical figures with a professional or the official source.

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