Watt for watt, an oil-filled radiator and a fan heater cost exactly the same to run. Both turn every unit of electricity they draw into heat in the room, so a 2kW oil-filled radiator and a 2kW fan heater each cost 52.6p an hour at full power at the October 2026 price cap of 26.32p per kWh.
What changes the bill is how many watts you run and for how long, and that comes down to the heat settings and the thermostat. We priced a Russell Hobbs 2kW oil-filled radiator against a Morphy Richards 2kW fan heater, both from Amazon UK on 28 September 2026.
The verdict, 28 September 2026
- At full power both cost 52.6p an hour. Four hours a night for a month is £63.17 either way.
- The Russell Hobbs radiator has three settings, 800W, 1.2kW and 2kW, which cost 21.1p, 31.6p and 52.6p an hour.
- An oil-filled radiator is not more efficient. It holds heat and gives it out after its element switches off, but it had to draw that energy first.
- The fan heater is £15 cheaper to buy (£34.99 against £49.99) and warms the air near it faster. Since the running cost at the same wattage is identical, there is no pence-back point for the radiator.
- The thermostat matters more than the type. In our audit of 35 heater bestsellers, 9 of the 24 sold on energy-saving language had no thermostat at all.
| Russell Hobbs 2kW oil-filled radiator | Morphy Richards HeatFlux 2kW fan heater | |
|---|---|---|
| 1 hour at 2kW | 52.6p | 52.6p |
| 4-hour evening at 2kW | £2.11 | £2.11 |
| 4 hours a day for 30 days | £63.17 | £63.17 |
| Lower settings | 800W (21.1p an hour), 1.2kW (31.6p) | None stated in the listing details we read |
| Thermostat | Yes | Yes |
| Timer | No | Yes |
| Price, 28 Sep 2026 | £49.99 | £34.99 |
Why the running cost is the same
A plug-in electric heater has one job, turning electricity into heat, and it does it with no loss. The element in an oil-filled radiator heats oil sealed inside the fins, and the fins warm the room. The element in a fan heater warms air that a fan blows out. Even the fan motor’s electricity ends up as heat in the room. Either way, 2 kWh in means 2 kWh of heat out, and at the October cap that is 52.6p.
That is why the heater aisle’s energy-saving language does not stand up. In our electric heater rankings we read 35 bestselling listings: 24 used energy-saving language, none stated what the heater costs to run, and 9 of those 24 had no thermostat. We called that the claim-control gap.
What the oil does and does not do
The oil stores heat. When the thermostat switches the element off, a warm radiator keeps giving out heat for a while, so the room temperature moves more gently. That feels better, and it means a radiator can sit on a thermostat without the blast-and-stop of a fan heater.
It does not save energy. Every unit of heat the oil gives out after the element stops, the element had to put in first. Over a whole evening the radiator and the fan heater use the same electricity to hold the room at the same temperature.
The trade is speed. A fan heater pushes warm air at you within a minute or two. An oil-filled radiator takes a while to warm its oil before the room notices, so it suits a room you heat for hours, and the fan suits a quick blast while you get dressed.
What actually lowers the bill
Run fewer watts. The Russell Hobbs radiator’s 800W setting costs 21.1p an hour, 40% of its full-power cost. If 800W holds the room at the temperature you want, that is where the saving is. A smaller heater does the same job: our cheapest whole-room pick, a 650W oil-filled radiator, costs 17.1p an hour.
Use the thermostat. A thermostat stops the heater drawing power once the room is warm. Without one, a 2kW heater runs at 52.6p every hour it is switched on. Our appliance running cost calculator shows the difference: at 60% of the time the four-hour evening falls from £2.11 to £1.26.
Heat the person, not the room, when you can. An electric blanket costs 1.8p an hour. Our electric blanket vs heater comparison has the figures.
Which one to buy
Buy the oil-filled radiator for a room you heat for hours at a time, such as a home office or a bedroom in the evening. Its lower settings let you run it at 800W, and it is quiet.
Buy the fan heater for short bursts in a cold room, or if the £15 matters. At the same wattage it costs the same to run, and the Morphy Richards adds a timer and a remote.
How we worked it out
| Item | What we did |
|---|---|
| Electricity rate | 26.32p per kWh, the Ofgem cap for 1 October to 31 December 2026, direct debit, Great Britain average. Standing charge left out. |
| Power | The rated heat output on each Amazon UK listing, read 28 September 2026: 2,000W for both, and 800W and 1.2kW for the radiator’s lower settings. |
| Cost | Watts × hours ÷ 1,000 × 26.32p, at full power the whole time. |
| A month | Four hours a day for 30 days. |
| Prices | Amazon UK, read 28 September 2026. |
| The pence-back point | None. At the same wattage the two cost the same per hour, and the fan heater is cheaper to buy. |
What this comparison could not check
- We have not run either heater on a meter. Every cost uses the listed heat output for the full time, the most each could cost.
- How long each thermostat keeps its heater switched on in your room.
- How quickly each one warms a real room, and how loud the fan is.
The two heaters
Russell Hobbs 2kW Oil Filled Radiator, 9 fin
£49.99. 52.6p an hour at 2kW and 21.1p on its 800W setting at the October 2026 cap. It has an adjustable thermostat, and the oil keeps giving out heat after the element switches off.
The catch: Slow to warm a room from cold, and no timer.
See it on AmazonMorphy Richards HeatFlux 2kW Upright Fan Heater
£34.99. 52.6p an hour at 2kW, the same as the radiator. It has a thermostat and a timer, comes with a remote, and heats the air near it quickly.
The catch: The warmth stops as soon as the element does, and a fan makes noise.
See it on AmazonLook Into earns a commission on qualifying purchases made through the Amazon links above, at no extra cost to you. It never changes the arithmetic.
Common questions
Is an oil filled radiator cheaper to run than a fan heater?
Not at the same wattage. Both turn all the electricity they use into heat, so a 2kW oil-filled radiator and a 2kW fan heater each cost 52.6p an hour at full power at the October 2026 cap of 26.32p per kWh.
Do oil filled radiators use a lot of electricity?
As much as their wattage says. A 2kW radiator uses 2 kWh an hour at full power, 52.6p. On an 800W setting it uses 0.8 kWh, 21.1p. A thermostat cuts that further by switching the element off once the room is warm.
Why do people say oil radiators are more efficient?
Because the oil keeps giving out heat after the element switches off, which makes the room feel steadier. That heat was paid for when the element was on, so it does not reduce the bill.
How much does a fan heater cost to run per hour?
A 2kW fan heater costs 52.6p an hour at full power at 26.32p per kWh. Four hours a night for a month is £63.17 if it never switches off.
Compare more
- All our running-cost head-to-heads
- Meaco Arete One vs Arete Two 12L: the Two is cheaper per litre in every room Meaco publishes
- Meaco Arete One vs Arete Two 20L: 0.7p a litre apart, and the Two costs £110 more on Amazon than direct
- Meaco Arete One 12L vs MeacoDry ABC 10L: same night, different cost per litre
- Meaco vs Pro Breeze 12L dehumidifier: one publishes its wattage, one does not
- Ninja Dual Zone AF300UK vs Philips 3000 Dual Basket: 3p a cook against a £28 price gap
- Ninja AF300UK vs Tefal Easy Fry Dual Zone: nine years of cooking to earn back £62
- Ninja AF300UK vs AF400UK: the bigger one costs more per cook and less per litre of drawer
- Electric blanket vs heater: 1.8p an hour against 17.1p and up
- Electric blanket vs hot water bottle: half an hour of blanket costs less than one kettle fill
- Best electric heaters UK, ranked by what they cost to run
- UK running cost index
Sources
- Ofgem, energy price cap unit rates and standing charges (1 October to 31 December 2026)
- Look Into, best electric heaters UK 2026: audit of 35 bestselling Amazon UK listings
- Amazon UK listings for the Russell Hobbs 2kW Oil Filled Radiator (B07V3FPGPP) and Morphy Richards HeatFlux 2kW Upright Fan Heater (B0FQK1PL4D), heat output, features and prices read 28 September 2026