What does a 2kW oil filled radiator cost per hour in the UK?

Heating By Ellen HartwellPublished 26 September 2026

What a 2kW oil filled radiator actually draws

There is no mystery in this appliance, which is part of why it is worth writing about. An oil filled radiator is an electric element sitting in a sealed column of thermal oil, and the element is either on or off. When it is on it draws the number on the plate, and 2kW means 2,000 watts.

Most of the range sold in Britain is built around that figure. De'Longhi lists its nine fin Radia S at 2,000 watts maximum, with switchable settings at 900 watts and 1,100 watts for milder weather. Dimplex builds the same output into its portable range, with 3kW models for larger rooms. Nothing in the oil changes the electricity used, since the oil is a heat store rather than a fuel and it is sealed in for the life of the machine.

That makes the arithmetic unusually honest. Whatever the plate says, divide by a thousand to get kilowatts, and that is what you buy for every hour the element is on.

The cost per hour and per evening

Two kilowatts for one hour is 2 kilowatt hours. At the Ofgem cap rate of 26.11p per kilowatt hour that is 52.2p. A 1500 watt setting costs 39.2p, the 1,100 watt middle setting costs 28.7p, and the 900 watt low setting costs 23.5p.

Very few people run one flat out for an hour, because the thermostat stops it. A cold living room takes perhaps twenty minutes at full output to reach temperature, after which the element cycles on and off to hold it. If it runs half the time across a four hour evening you have used 4 kilowatt hours and spent £1.04 rather than the £2.09 the plate rating suggests.

Run it for five hours a day through a heating season and the month reaches 303 kilowatt hours and £79.20, which is the number that gets people searching in the first place. Readers in the United States can take the same 2 kilowatt hours against the EIA residential average of 18.34 cents per kilowatt hour, which is about 37 cents an hour, or 69 cents in California.

Rates: Ofgem cap 1 July to 30 September 2026 at 26.11p per kWh (source), EIA residential average June 2026 at 18.34 cents per kWh (source). Checked 2026-09-22.

Why every electric heater costs the same per kilowatt

This is the part the adverts work hardest to hide. An oil filled radiator, a fan heater, a convector, a halogen bar and an expensive German panel heater are all resistive elements, and every one of them turns 100 per cent of the electricity into heat in your room. There is no efficiency to compete on, so a 2kW heater of any description costs 52.2p an hour.

What separates them is where the heat goes and how long it stays. A fan heater pushes hot air at you and stops dead the moment the thermostat cuts, so the room temperature swings. An oil filled radiator takes twenty minutes to feel warm and then keeps radiating for twenty minutes after the element stops, which lets the thermostat stay off for longer stretches. Across an evening that difference is worth real money even though the headline rate is identical.

The one genuine exception is a heat pump, which moves heat rather than making it and delivers three or four kilowatts of warmth for one kilowatt of electricity. Nothing you can buy with a plug on it does that.

Against gas central heating

Gas costs 7.33p a kilowatt hour on the current cap against 26.11p for electricity, so a decent condensing boiler delivers useful heat at around 8p a kilowatt hour once you allow for efficiency. That is roughly a third of the price of the same heat from a socket.

The radiator still wins in one situation, and it is a common one. If you want a single room warm for three hours and the alternative is firing the boiler for a whole house with fifteen radiators, the portable heater is the cheaper choice by a wide margin. Turn the room count up to three and the boiler is back in front.

The gas standing charge of 29.04p a day is worth remembering here too, because it is paid whether or not the boiler ever fires. Households that switch to electric heaters for a whole winter to dodge the boiler discover that they are still paying £26 a quarter for the privilege of having gas.

Six ways to cut what it costs you

• Use the timer so the room is warm when you walk in, rather than leaving the heater running to keep an empty room at temperature.
• Set the thermostat dial to the lowest setting that feels comfortable, since every degree you drop cuts the hours the element has to run.
• Choose the 900 or 1,100 watt setting in mild weather, because a lower output running steadily is cheaper than full output cycling hard.
• Close the door and the curtains in the room you are heating, as a portable heater competing with a draughty hallway never gets to switch off.
• Put the radiator against an internal wall rather than under a window, where half the heat goes straight through the glass.
• Check the tariff. At 26.11p a kilowatt hour a 2kW heater is the most expensive appliance in most houses, so a time of use tariff with a cheap overnight window changes the maths more than any heater ever will.

Is it worth having one at all

For heating one room in a house with a working boiler, an oil filled radiator is a good tool used badly by most people who own one. Used for three hours in the evening in a closed room it costs about £1 a night and saves firing the whole system.

Used as a substitute for central heating through a winter it is the most expensive heat you can buy short of a plug in electric shower, and the bill lands eight weeks later when it is too late to change anything.