Cheapest way to heat a room: fan heater vs oil-filled radiator vs infrared vs air-to-air heat pump

The cheapest way to heat a room with electricity is an air-to-air heat pump, by a wide margin. On the Ofgem price cap for 1 July to 30 September 2026 (26.11p/kWh), 2kW of heat costs 52p an hour from a fan heater, an oil-filled radiator, a convector, a panel heater, or an infrared panel, because they all turn electricity into heat at exactly 100%. A wall-mounted split delivering the same 2kW draws a quarter to a fifth of the electricity and costs 10p to 13p an hour. Mains gas is cheaper still per unit of heat, at roughly 8p per kWh through a modern boiler, but only if you are happy to run the whole house to warm one room.

That is the short answer. The longer one is about how many hours you will run the heater and what you are prepared to spend up front. A £10 fan heater is the right buy for a spare room you use twice a month and the wrong one for a home office you sit in five days a week. This guide gives you the maths to tell the difference.

Why every plug-in heater costs the same to run

There is a persistent belief that some electric heaters are "more efficient" than others. They are not. The Centre for Sustainable Energy puts it plainly: electric heaters are "100% efficient because all the electricity used is converted into heat", and then adds the important second half, "this doesn't mean they are cheap to run".

A 2kW fan heater and a 2kW oil-filled radiator both draw 2kWh in an hour at full power, and 2kWh at 26.11p is 52p. The wattage on the box dictates the cost. What differs is how the heat arrives (radiant heaters warm you straight away, convection heaters warm the air and keep it warm), whether the thermostat lets the heater rest, and how many hours you run it. The only electric appliance that escapes the 100% ceiling is a heat pump, because it moves heat from outside rather than making it.

A 2kW fan heater and a 2kW oil-filled radiator cost exactly the same 52p an hour. Nothing on the box changes that. Only a heat pump does.

Cost per hour, per evening, and per winter: the full table

Assumptions: Ofgem price cap, 1 July to 30 September 2026, direct debit, electricity 26.11p/kWh and gas 7.33p/kWh. Every heater runs at full rated output for the whole hour, the worst case. A "winter" is 5 hours a day for 120 days, 600 hours. Purchase prices are supply-only bands from UK retailers in September 2026 unless stated.

Rates correct as of September 2026 at 26.11p/kWh electricity and 7.33p/kWh gas (Ofgem cap, 1 July to 30 September 2026). October's price cap moves electricity to 26.32p/kWh and gas to 7.97p/kWh, which adds a fraction of a penny an hour and changes nothing in the ranking.

The heat pump rows use the sum: electricity drawn = heat wanted divided by SCOP. So 2kW of heat at SCOP 4.0 is 0.5kWh, and 0.5 x 26.11p is 13p. The gas row assumes a 90% boiler, the figure Nottingham Energy Partnership uses in its fuel comparison. The storage heater row uses the 15.43p/kWh off-peak rate Which? quotes as the January 2026 Economy 7 average, and the log burner row uses Nottingham Energy Partnership's August 2026 figure of 10.73p per kWh of heat from kiln-dried logs.

Real bills will be lower than the table for anything with a thermostat, because the heater rests once the room is warm. An inverter split does the same, running hard for the first 20 to 30 minutes and then throttling back. For your own room and hours, use the running cost calculator.

Fan heater vs oil-filled radiator

This is the comparison most people are actually making. Per hour at the same wattage they cost the same: 2kW of either is 52p. The 1.5kW oil-filled radiator in the table is cheaper only because it is smaller.

The difference is how they behave over an evening. A fan heater gets warm air on you within seconds and suits 20 minutes in a cold bathroom. It is noisy, and the moment it stops the room is cold again. An oil-filled radiator takes 15 to 20 minutes to get going, is silent, and keeps radiating after the thermostat clicks off, so it cycles less over a long evening; the Centre for Sustainable Energy calls it "a good option for heating one room". It costs three or four times as much to buy.

For a couple of hours a week, buy the fan heater. For a room you sit in every evening, the oil-filled radiator is more comfortable and will probably use a little less electricity over the winter. Neither is cheap to run; they are simply cheap to buy.

Are infrared panels cheaper to run?

Per kilowatt, no. A 2kW infrared panel costs 52p an hour like everything else with a 2kW element. Herschel, which describes itself as the UK's leading infrared manufacturer, accepts that "all electric heaters are already 100% efficient" under building specifications, and then argues that a smaller panel can keep you comfortable at a lower room temperature because it warms you directly rather than the air.

There is something in that for the right room. A 600W panel above a desk costs 16p an hour and keeps the person at the desk warm. It will not heat the room; for the whole space at 20°C you need 1.5kW to 2kW of panels and you are back to fan-heater money. Infrared is a comfort choice, not a running-cost one, and we go through it properly in infrared heating panels vs air-to-air heat pumps.

Halogen heaters, electric fires, and storage heaters

Halogen heaters are the cheapest electric heater to run per hour because they are low-wattage, typically 400W to 1.2kW, which Ideal Home's 2026 comparison puts at 11p to 33p an hour. They warm whatever they point at and nothing else.

Electric fires are a heater with a light show. Heat output is typically 1.4kW to 1.6kW, which costs 37p to 42p an hour, while the LED flame effect alone draws 10W to 30W, under 1p an hour.

Storage heaters are different because of the tariff. They charge overnight on Economy 7 at an off-peak rate around 15p/kWh and release heat during the day, which makes them the cheapest resistive electric heating per kWh, and the Centre for Sustainable Energy rates high-retention models as one of the cheapest electric methods when used correctly. The catch is that the heat arrives on the heater's schedule, and a basic model has often run out by 8pm. Around 1.7 million UK homes still heat this way, and for most of them a heat pump is the upgrade that pays; see replacing storage heaters with an air-to-air heat pump.

Is gas central heating cheaper than an electric heater for one room?

Per unit of heat, gas wins comfortably: about 8.1p per kWh through a 90% boiler, against 26.1p from any plug-in heater and 5.2p to 6.5p from a heat pump at SCOP 4 to 5.

The problem is that you cannot buy 2kW of gas heat for one room. Turning the boiler on runs the pump, fires the burner, and pushes hot water round every radiator that is not turned off. MoneySavingExpert's rule of thumb is that a single electric heater for a short blast can be cheaper, but "if you want to heat multiple rooms, or one room for longer periods of time, your central heating is likely to be more efficient". The Centre for Sustainable Energy calls fan heaters "the biggest energy guzzlers" and says that for a few hours "it may be cheaper just to turn on your gas central heating with the radiators on a low setting in the rooms you're not using".

If you have gas, turn up the thermostatic valve in the room you use and down elsewhere, and keep a fan heater for emergencies. If you do not have gas, which is most flats on storage heaters and most garden rooms, the choice is between a plug-in heater and a heat pump, and that is where the sums get interesting.

Log burners: cheap wood, expensive stove

A log burner is not a way to save money on one room. Kiln-dried logs work out at around 10.7p per kWh of heat through an 85% efficient stove on Nottingham Energy Partnership's August 2026 figures, so an evening burning at 3kW costs about £1.61: more than a heat pump, less than a fan heater. The stove is the expense. Checkatrade puts a stove at £500 to £1,500 and installation at around £2,000, so about £3,000 before you have burned a log.

Then there are the rules. Since January 2022 every new stove sold in the UK must be Ecodesign compliant, and firewood sold in small volumes must be Ready to Burn (20% moisture or less). DEFRA describes home stoves and open fires as "a major contributor" of fine particulate matter, PM2.5, and in a smoke control area its guidance is blunt: "you could be committing an offence if smoke is released from the chimney of your home." Fit one because you want one, not to cut a bill.

When a £10 fan heater is the right answer

Sometimes it is, and the maths is entirely about hours. A spare room, bathroom, or workshop used ten hours a month costs £5.22 at 52p an hour; an installed split would take decades to pay back. A rental you will leave within a year or two is the same story, and a good oil-filled radiator with a thermostat and timer is the sensible buy. In a house with gas central heating, a halogen or small infrared panel aimed at the sofa costs pennies and stops you turning the whole house up.

Two cautions. Which? found heaters sold through social media and marketplaces that risked "electric shock, fire or explosion"; buy a branded one from a proper retailer. And keep any heater clear of curtains and bedding, never cover it, and do not leave it running while you sleep.

When an air-to-air heat pump pays back

The moment you heat a room every day, the sums flip. Take a home office heated five hours a day through the winter:

At 26.11p/kWh (Ofgem cap, 1 July to 30 September 2026), full output for every hour. A thermostat-controlled heater and an inverter split both cost less in practice.

Against a 2kW panel heater a split saves around £240 a winter for the same heat, more if you run it longer, heat a bigger room, or heat two rooms from a multi-split. A single wall split supplied and fitted costs £1,500 to £3,000, so on a five-hour-a-day office the running-cost saving pays for the unit in six to twelve winters, before you count that it also cools the room in July. Retailers list the Daikin Perfera FTXM25A at SCOP 5.2 with an A+++ heating label and the Mitsubishi Electric MSZ-AP25VGK at SCOP 4.8; both heat well below freezing, with output falling as the temperature drops. Full pricing is in air-to-air heat pump cost.

A split is the right answer when you heat the room most days for three hours or more, when the home has no gas (a flat on storage or panel heaters, an annexe, a garden room), or when you want cooling as well. Every wall split sold in the UK is a reverse-cycle unit that does both.

Two things before you get quotes. Refrigerant work must be done by an F-Gas certified installer, and permanently fixed air-to-air heat pumps are zero-rated for VAT until 31 March 2027. The £2,500 Boiler Upgrade Scheme grant for air-to-air units exists on paper, but as of September 2026 MCS is still completing the scheme and almost no households have received it, so budget without it and read the grant guide for the current position. For how a split behaves in heating mode see heating with air conditioning, and start with our air-to-air heat pumps guide if you are new to the idea.

Comfort and safety, briefly

Heating one room and leaving the rest cold has a side effect the Centre for Sustainable Energy flags: condensation and mould in the unheated rooms. Keep the rest of the home ticking over at a low temperature if you can, and ventilate. Whatever you buy, get a thermostat and a timer, and set the timer to come on about half an hour before you need the room. A heater running unattended at full power all evening is the expensive habit, not the heater itself.

Prices and rates correct as of September 2026. Heater prices are September 2026 retailer snapshots; the energy price cap changes quarterly, so check current rates before budgeting. See more air conditioning cost guides.