How Much Does It Cost to Run an Electric Heater?

By the HomeMathCalc Team · Updated 26 October 2026

Short answer: at the Ofgem price cap average of 26.32p per kWh (1 October to 31 December 2026), a 2 kW electric heater costs about 52.6p an hour on full power. Used 4 hours a day, that is £2.11 a day and £189.50 over a 90-day winter. A 1 kW heater costs half that.

The running cost formula

Every electric heater turns electricity into heat, so the cost depends only on its power in watts, how long it runs and what you pay per unit (kWh).

The power is printed on the rating plate, usually as 2 kW or 2,000 W. Many heaters have two or three settings (for example 1 kW and 2 kW), so use the setting you actually run it on.

Cost per hour, day and winter by heater size

All figures use 26.32p per kWh, the Ofgem price cap average unit rate for Direct Debit customers from 1 October to 31 December 2026, and assume the heater runs at full power.

The type of heater does not change the cost per kWh. A 2 kW fan heater, a 2 kW convector and a 2 kW oil-filled radiator all use 2 kWh in an hour on full power. What differs is how quickly they warm a room and how they hold heat once the thermostat switches off.

How hours of use add up (2 kW heater)

If your unit rate is different

Fixed tariffs and regional prices vary, so check the unit rate on your bill. For a 2 kW heater used 4 hours a day for 90 days:

These are unit costs only. Under the price cap you also pay a standing charge of 54.83p a day on average, which is £200.13 a year. You pay it whether the heater is on or not, so it does not change the cost of running the heater itself.

Worked example: heating a home office

You work from home and run a 1.5 kW oil-filled radiator for 6 hours a day, 5 days a week, from October to March: about 130 days.

Energy per day: 1.5 × 6 = 9 kWh. Cost per day: 9 × 26.32 ÷ 100 = £2.37. Over 130 days that is 1,170 kWh and £307.94.

That figure assumes the radiator never switches off. Once the room is warm, the thermostat cuts the power on and off. If it only draws power half the time, the cost halves to £153.97. You can see your real figure by reading the meter, or a plug-in energy monitor, before and after a day of use.

Practical tips

• Use the thermostat and timer. The tables show the worst case at full power. A heater that cycles off when the room reaches temperature costs less.
• Heat the room, not the house. A portable heater makes most sense for one room for a few hours, such as a home office, while the central heating stays lower.
• Lower settings help. Running a 2 kW heater on its 1 kW setting halves the hourly cost, if it keeps the room warm enough.
• Close doors and curtains. Less heat lost means the thermostat switches off sooner.
• Compare with other appliances. Work out any appliance with the electricity cost calculator. If you are thinking about cutting bills long term, see the solar panel calculator.

Try the electricity cost calculator (uk)

Enter your own numbers below, or open the full electricity cost calculator (uk) with the formula and more examples.

This guide is general information with example numbers, not financial, tax or building advice. Your costs and results will differ. Terms

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