There is an old principle in keeping warm cheaply: heat the person, not the building. An electric blanket is the clearest example of it. Warming the small space immediately around your body costs a tiny fraction of bringing a whole house, or even a single bedroom, up to temperature. On a cold night the gap in cost is enormous for very similar comfort. This guide puts real numbers on that gap, covers the forms a blanket comes in, the safety points that matter, and the times when heating the room is still the right call.
The short answer. An electric blanket or heated throw draws roughly 50 to 150W, which costs about 1p to 4p an hour at 26.11p per kWh. Heating a room with a 2kW electric heater costs about 52p an hour, and running gas central heating for the whole house costs pounds. For one or two people sitting still, or warming a bed, the blanket wins easily. Heating the room still matters when several people are spread about or the house needs to stay above damp-forming temperatures.
Why heating the body wins on cost
To warm a room you have to heat all the air in it and, through that, the walls, furniture and everything else. Much of that warmth then leaks away to the colder outdoors and has to be replaced again. An electric blanket skips all of that and puts a modest amount of heat exactly where you are.
A typical electric blanket or heated throw draws somewhere between 50 and 150W, against the 2,000 to 3,000W of a fan heater or the far larger output of central heating. That is a factor of twenty or more. The difference in running cost follows directly from those wattages, because what you pay is simply power times time times the unit rate. Put the figures into the running cost calculator and the gap is stark: a few pence for an evening under a blanket, against pounds for heating the house.
The physics is on the blanket's side too. A heated room is constantly losing warmth through the walls, windows and ventilation, so you keep paying to top it back up. A blanket loses almost nothing, because the heat is trapped against you under the covers, so nearly every watt does useful work. This is the same logic as heating one room rather than the whole house, taken to its cheapest conclusion. You are heating one person, and barely losing any of it.
The running-cost comparison
Here is a like-for-like look at a winter evening, four hours from after dinner to bedtime, plus warming the bed. The blanket figures assume it runs on a middling setting; in practice most blankets cycle on and off, so real use is often lower still.
| Way of keeping warm | Power | Cost for 4 hours |
|---|---|---|
| Heated throw on the sofa | ~100W | ~10p |
| Underblanket on a low setting | ~60W | ~6p |
| 2kW oil-filled electric radiator | 2,000W | ~£2.09 |
| 3kW fan heater, flat out | 3,000W | ~£3.13 |
| Gas central heating, whole house | ~8 to 12 kWh/hr gas | ~£2.35 to £3.52 |
At 26.11p/kWh electricity and 7.33p/kWh gas, Ofgem cap July to September 2026. Worked examples; check your own tariff.
Warming the bed with an underblanket for half an hour before you get in costs under a penny. Heating the bedroom to stay comfortable all night costs far more. The blanket does not replace heating the house entirely, but it lets you heat it less, and that is where the saving lands. Drop the thermostat a degree or two because your body is warm, as the thermostat settings guide describes, and you save on top of the few pence the blanket draws.
Underblanket, overblanket and heated throws
There are a few forms and they suit different uses. An underblanket sits on the mattress beneath the sheet and warms the bed, often used to take the chill off before you get in and then switched off or turned low to sleep. An overblanket lies on top like a duvet and warms you as you lie under it. A heated throw is a portable version for the sofa, draped over you while you watch television or read.
All work on the same cheap principle. A heated throw in particular can let you keep the living-room heating lower through an evening because you are warm under it regardless. If you mainly want to cut the chill of a cold bed, an underblanket used only for pre-warming costs almost nothing across a whole winter, perhaps 5p a week if you run it half an hour a night. If you want all-evening warmth on the sofa, a throw is the one to buy. They are a more comfortable, more targeted version of the heat-the-person idea than a portable heater warming the whole room.
Wattage and settings matter more than the type. A throw left on its highest setting all evening still only costs a few pence, but a cheap, well-chosen blanket on a low or medium setting is all most people need once they are under the covers. The heat builds up and holds, so you rarely need full power for long. If you are choosing between models, the lower the wattage you can be comfortable at, the cheaper it runs, and most of the comfort comes from trapping warmth rather than pumping out more of it.
How a blanket compares with a heat pump or storage heater
The blanket is unbeatable for one or two people sitting still, but it is worth being honest about where it sits in the wider heating picture. It does not warm a room, so it does nothing for activity, for several people, or for keeping the building itself above the temperature where damp forms.
If your whole-house heating is expensive electric, say old storage heaters or panel heaters, the blanket saves a great deal because you are displacing electricity with much less electricity. If you heat with gas or a heat pump, the per-unit heat is cheaper, so the blanket's advantage is about heating a smaller target rather than a cheaper fuel. Either way the principle holds: warm the person first, then heat the room only as much as the rest of the household and the building actually need.
Safety, which matters here
Electric blankets are safe when looked after, but they deserve respect because they combine electricity, heat and bedding. Buy one carrying the proper UK safety marks, check it regularly for fraying, scorch marks or damaged wiring, and replace an old or worn one rather than nursing it along.
Follow the instructions on whether it can be left on overnight. Many modern underblankets are designed for all-night use on a low setting, while older or cheaper ones are meant only for pre-warming and should be switched off before you sleep. Do not use a blanket that is creased or folded in a way the maker warns against, keep it flat, and never combine an electric blanket with a hot-water bottle. If a blanket is more than ten years old, or shows any sign of wear, retire it. The few pounds a replacement costs is nothing against the risk, and a worn blanket is the one corner you should never cut for a saving.
When each makes sense
Heating the person is the smart, cheap choice when one or two people are sitting still in the evening or warming a bed, which is most of the time this question comes up. A heated throw and a slightly lower thermostat is hard to beat for a quiet evening in.
Heating the room or house properly still matters when there are several people spread around, when you need the whole space comfortable for activity rather than sitting, or to keep the building above the point where damp and cold cause problems. The two work together: keep the house at a sensible base temperature, then top up your own comfort cheaply with a blanket or throw rather than cranking the heating for everyone. For more on warming people rather than air, see whether it is cheaper to heat one room or the whole house, and for the cheap fabric fixes that make any heating go further, the draught-proofing and curtains for warmth guides.