What Is the Cheapest Way to Heat One Room in the UK?

What is the cheapest way to heat one room? Whether you’re working from home in a freezing spare room, trying to avoid heating the whole house for one person, or topping up a cold spot the radiators can’t reach, the answer matters — because heating one room badly can cost more than heating the whole house well.

I work from home in a north-facing box room, and I’ve tested nearly every option below over three winters. The results surprised me — the cheapest heater isn’t always the cheapest heating.

The maths: cost per hour of heat

All electric heaters cost the same per unit of heat — electricity is ~24p/kWh (price cap), so a 2kW heater costs ~48p/hour to run regardless of type. The difference is how effectively that heat warms you, and for how long after switch-off. Gas central heating costs ~6p/kWh — roughly a quarter of electricity. This single fact dominates everything below.

Cheapest way to heat one room: the options ranked

1. Your existing gas radiator + closed door (cheapest). If the room has a working radiator, just use it and keep the door shut. Even heating one extra radiator on the gas system costs a fraction of any electric heater. Turn TRVs down elsewhere. This wins by a mile — see our broader guide to reducing your heating bill in winter for the full strategy.

2. Oil-filled radiator (~£40-80 to buy). The best electric option for sustained heating. Slow to warm up (20-30 minutes) but retains heat well, doesn’t dry the air, silent, and safe to leave on low. A 1.5kW oil radiator on a thermostat costs ~25-35p/hour in practice. Best for: home offices, bedrooms — anywhere you sit for hours.

3. Electric heated throw / blanket (~£30-60 to buy). The dark horse. Heating you instead of the room uses 100-150W — about 3p/hour. For sofa evenings and desk work, nothing touches it for cost. Not a room heater, but often all you actually need.

4. Halogen / infrared heater (~£25-50). Heats objects and people directly, not air — instant warmth, ~30-40p/hour for a 1.2kW model. Best for: quick warm-ups, draughty rooms where convection heat escapes. Downsides: intense directional heat, dries air, and the glow annoys some people.

5. Fan heater (~£20-40). Cheap to buy, expensive to run, noisy, dries the air horribly. Fine for a 10-minute bathroom warm-up; terrible as a sustained solution. The 2kW blast costs 48p/hour and the heat vanishes the moment you switch off.

6. Portable gas / paraffin heaters. Cheap heat per kWh but produce moisture and carbon monoxide risks — need ventilation, which defeats the purpose. I don’t recommend them for regular indoor use.

The real answer: heat yourself first

The cheapest “heating” is no heating: a heated throw (3p/hour), thermal base layers, a hot water bottle, and draught-proofing the room (how to stop draughts). My home-office setup is an oil radiator on low plus a heated throw — total running cost under 20p/hour, and I’m genuinely warm. Compare that with blasting a 2kW fan heater at 48p/hour while still feeling cold.

When one-room heating makes sense (and when it doesn’t)

One-room electric heating makes sense for: a home office used 8 hours while the rest of the house is empty, topping up a room the central heating can’t reach, and short-term situations. It doesn’t make sense as a whole-winter strategy for a lived-in house — at that point, running the gas central heating properly (heating on low all day vs timed) is cheaper and far more comfortable. And if the room is cold because of poor insulation, fix that instead — see loft insulation costs and insulation grants.

Buy right if you’re buying

If you do buy an electric heater: get one with a thermostat and timer (running full-blast constantly is where the money goes), tip-over protection, and the right size — 1-1.5kW for a small room, 2kW for a large one. An oil-filled radiator with a thermostat is the best all-rounder for sustained use; a heated throw is the best value per unit of comfort. Either way, check the Which? reviews before buying — build quality varies enormously at the cheap end.

Safety: heaters and fire risk

Portable heaters cause hundreds of UK house fires a year, so take safety seriously: keep all heaters at least a metre from curtains, furniture and bedding; never drape clothes over them; plug directly into the wall (not extension leads — heaters draw high current and cheap extensions overheat); and never leave them on unattended or while sleeping unless they’re specifically designed for it (oil-filled radiators with thermostats and tip-over protection are the safest category).

Buy from reputable brands with proper UKCA/CE marking — the ultra-cheap unbranded heaters on marketplace sites are the ones that appear in fire reports. And if you have an open fire or wood burner as an alternative, that’s often the cheapest room heat of all — but that’s a different guide.

Fix the room, not just the heating

A room that needs supplementary heating often has a fabric problem worth fixing: single-glazed windows (secondary glazing film, £10-15), draughty frames (draught-proofing guide), uninsulated external walls, or a cold floor (a thick rug with underlay makes a remarkable difference on suspended timber floors). Spending £50 fixing the room beats spending £50 a month heating the outdoors.

Check the basics too: is the room’s radiator actually working? A bled, balanced radiator with the TRV set properly (bleeding guide) might eliminate the need for supplementary heating entirely. The cheapest heater is the one you don’t need to buy.

Quick answers

How much does it cost to run a 2kW fan heater for an hour?
About 48p at the current ~24p/kWh price cap — and fan heaters are the least efficient-feeling option since the heat dissipates instantly. An hour a day through winter adds ~£85 to your bill. This is why they’re for warm-ups, not sustained heating.

Are oil-filled radiators expensive to run?
They cost the same per kWh as any electric heater (~24p), but their thermostat cycling and heat retention mean lower real-world costs — typically 20-35p/hour for a 1.5kW model maintaining temperature, versus 48p/hour for a fan heater blasting constantly.

Can I heat one room with the central heating off?
Technically yes if the room has its own radiator and you close other TRVs — but boilers don’t like running with most radiators closed, and you’ll still pay the standing charge. It’s usually cheaper to run the whole system efficiently than to game it room by room.

The hierarchy

Cheapest way to heat one room in the UK: use the gas radiator you’ve already got. Next best: heat yourself (heated throw, layers) plus an oil-filled radiator on a thermostat for background warmth. Avoid fan heaters for sustained use, and don’t let one-room electric heating become a whole-house strategy — the maths never works at 24p/kWh.