Oil-filled electric radiators: running costs and how to choose one
By Dale @ ukaircontracker · facts checked
Quick answer
An oil-filled radiator is a plug-in electric heater: an element warms sealed oil, which holds and spreads the heat. The oil is never used up. At the 26.32p/kWh price cap a 1.5 kW model costs 39p an hour at full power, 2 kW costs 53p and 2.5 kW costs 66p. Once the room warms, the thermostat cycles the element and the cost falls.
| Rating | Per hour | 5 hours a day | Room size it suits (rough guide) |
|---|---|---|---|
| 1 kW | 26p | £1.32 | Small bedroom or study |
| 1.5 kW | 39p | £1.97 | Average bedroom |
| 2 kW | 53p | £2.63 | Living room |
| 2.5 kW | 66p | £3.29 | Large or draughty room |
At 26.32p/kWh (Ofgem cap, Oct–Dec 2026). Real cost is lower once the thermostat starts cycling.
De'Longhi Dragon 4 Oil-Filled Radiator 2kW
Photographed listing — tagged buy buttons go to the retailer, not another article.
Are oil radiators cheaper than other electric heaters?
Every plug-in electric heater turns one unit of electricity into one unit of heat, so a 2 kW oil radiator and a 2 kW fan heater cost the same per hour at full power. The oil radiator's advantage is gentle, steady heat and a thermostat that holds the room temperature without overshooting. A fan heater warms a room faster, which suits short bursts.
Choosing one
- Pick wattage for the room, not the biggest available: an oversized heater just cycles more.
- A digital thermostat and timer save more money than any other feature.
- Look for tip-over and overheat protection, and keep it clear of curtains and drying clothes.
Look at the kit — then buy it
De'Longhi Dragon 4 Oil-Filled Radiator 2kW
Dimplex 2kW Oil-Filled Radiator
Pro Breeze OmniWarm Smart 2500W 11 Fin Oil Filled Radiator
We earn a commission if you buy through links on this page, at no extra cost to you. As an eBay Partner Network affiliate and an Amazon Associate, we earn from qualifying purchases. Links we earn from are marked “affiliate link”. Used and refurbished eBay listings are labelled as such. Full disclosure.
Common questions
- Do oil filled radiators use a lot of electricity?
- A 2 kW model uses 2 kWh an hour at full power, 53p at the current price cap. With the thermostat cycling, the average is usually lower.
- Do you need to refill the oil in an oil filled radiator?
- No. The oil is sealed in at the factory and is only a heat store. It never needs topping up.
- Is it safe to leave an oil filled radiator on overnight?
- Follow the manufacturer's instructions. Fire services generally advise not leaving heaters on while you are asleep or out; if you must, use a timer, keep it clear of fabric and choose one with overheat and tip-over protection.