- An electric heater costs 26.3p an hour at 1 kW, 52.6p at 2 kW and 79p at 3 kW, if it runs at full power for the whole hour.
- Prices from the Ofgem price cap, 1 October to 31 December 2026: the average for England, Scotland and Wales is 26.32p per kWh by Direct Debit. Your region and tariff change it, so use the calculator below.1
- Last checked: 28 October 2026.
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How much does an electric heater cost per hour?
Here is the cost at 1 kW, 2 kW and 3 kW for 15 minutes, 1 hour and 3 hours of full-power use.
| Power | 15 minutes | 1 hour | 3 hours |
|---|---|---|---|
| 1 kW | 6.6p | 26.3p | 79p |
| 2 kW | 13.2p | 52.6p | £1.58 |
| 3 kW | 19.7p | 79p | £2.37 |
How to work out the cost
Multiply the power in kilowatts by the hours it runs, then by your electricity unit rate. If the power is in watts, divide by 1,000 first.
For example: 2 kW x 3 hours x 26.32p per kWh = £1.58.1
That is the cost at full rated power. If a thermostat switches the appliance off once the room is warm, it uses less. Standing charges are paid whatever you use, so they are not part of the cost of switching it on.
What the kW rating means
The kW figure is the most power the heater uses. A thermostat switches it off once the room reaches the set temperature, so it often uses less than the full figure over an hour.
Two examples of published ratings: the Dimplex ML3TSTie7 convector heater is listed with “3kW of heat output”2, and the Dimplex FX20VE wall-mounted fan heater can be set to 1 kW or 2 kW when it is installed (it is “factory set for 1kW operation”).3 Models are named only as examples of published ratings, not recommendations.
Which type of electric heater is cheapest to run?
For the same power and the same hours, the cost is the same whatever the type: 2 kW for 1 hour costs 52.6p whether it comes from a fan, convector, oil-filled or halogen heater.
What changes the bill is the power setting you choose, how long it runs, and whether a thermostat or timer switches it off. A lower setting uses less electricity and gives out less heat.
Compare: 79p for 3 hours at 1 kW, against £2.37 for 3 hours at 3 kW.
Using a portable heater safely
Electrical Safety First says: “Never leave your heater unattended while in use or while you are asleep.” and “It is recommended not to use a portable heater overnight.”4
It also says to “Keep all combustible materials at least one metre away from the heater”, to “avoid powering a heater from an extension lead as they can easily be overloaded”, and: “Never dry clothes directly on or close to your heater.”4
Next steps
1. Find the power on the heater's rating plate or in its manual (W or kW).
2. Find your electricity unit rate on your bill or in your supplier's app.
3. Put both into the calculator above, with the hours you use it.
4. Use the lowest setting that keeps you warm, and a thermostat or timer if it has one.
Help with energy bills
If you are struggling with energy bills, check the help you may be able to get. These checkers are free and need no account.
Who these figures cover
The prices are from Ofgem's price cap for England, Scotland and Wales, 1 October to 31 December 2026.1 In Northern Ireland, use the unit rate on your bill in the calculator.
There is no VAT on household electricity in England, Scotland and Wales, and the rates above already reflect this.1 HMRC: “The temporary zero rate applies from 1 October 2026 to 30 June 2027.” The Budget on 28 October 2026 extended it from 31 March (announced; the legislation is due in early 2027). Gas stays at 5% VAT.6