- An oil-filled radiator costs 39.5p an hour at 1.5 kW and 52.6p at 2 kW, at full power. On a lower setting of 700 W it is 18.4p an 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 oil-filled radiator cost per hour?
Costs at the power settings of two published models, for 1, 3 and 8 hours at full power on that setting.
| Power | 1 hour | 3 hours | 8 hours |
|---|---|---|---|
| 700 W | 18.4p | 55.3p | £1.47 |
| 900 W | 23.7p | 71.1p | £1.90 |
| 1.5 kW | 39.5p | £1.18 | £3.16 |
| 2 kW | 52.6p | £1.58 | £4.21 |
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: 1.5 kW x 3 hours x 26.32p per kWh = £1.18.1
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.
Typical oil-filled radiator power
The De'Longhi Radia S TRRS0715 has a maximum of 1,500 W and a minimum of 700 W, with 3 power settings.2 The larger TRRS0920 goes up to 2,000 W, with a minimum of 900 W.3 Models are named only as examples of published ratings, not recommendations.
Running on the lowest setting rather than the highest makes a real difference: 3 hours costs 55.3p at 700 W, against £1.18 at 1,500 W.
Is an oil-filled radiator cheaper than other electric heaters?
Not for the same power and hours: 1.5 kW for an hour costs 39.5p from any electric heater. The oil holds heat for a while after the element switches off, which can mean the thermostat switches it on less often, but how much depends on the room.
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. Check the power settings on your radiator's label or manual.
2. Start on the lowest setting that keeps the room comfortable.
3. Put the setting and your hours into the calculator above, with your region.
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