How much does it cost to run an electric blanket per hour in the UK?
A 70 watt single electric underblanket costs 1.8p an hour at the Ofgem cap rate of 26.11p per kWh, and a king size on its highest setting at 90 watts costs 2.3p. Measured on the low setting people actually sleep with, 28 watts, the same blanket costs 0.7p an hour and 5.9p for a full eight hour night.
What an electric blanket actually draws
The rating on the control box is the maximum, reached only while the blanket is warming up, and the setting you sleep on matters far more than the model you bought.
Silentnight rates the single size of its Comfort Control underblanket at 70 watts. Independent bench testing of the same product measured 28 watts on setting one and 51 watts on setting two, with the king size reaching 90 watts on setting three. That spread, from 28 to 90 watts, covers nearly every underblanket sold in Britain, which is why this page does not change much between brands.
Overblankets and heated mattress toppers sit slightly higher because there is more fabric to warm, and the old style blankets with a rotary dial rather than a digital controller run at a fixed output rather than cycling, so they sit near the top of their range all night.
Work it out for your own electric blanket
Type in the wattage from the plate on the back, then your own unit rate. The numbers update as you type.
The cost, by setting
| Setting | Power | Per hour | Half hour preheat | Eight hour night | Month of nights |
|---|---|---|---|---|---|
| Setting one, single | 28 W | 0.7p | 0.4p | 5.9p | £1.75 |
| Setting two, single | 51 W | 1.3p | 0.7p | 10.7p | £3.20 |
| Full rating, single | 70 W | 1.8p | 0.9p | 14.6p | £4.39 |
| Setting three, king | 90 W | 2.3p | 1.2p | 18.8p | £5.64 |
| 2kW bedroom heater | 2,000 W | 52.2p | 26.1p | £4.18 | £125.33 |
The bottom row is what the blanket is replacing. Every row above it costs less for a whole eight hour night than the heater costs in its first half hour.
| Appliance | Typical draw | Usage we assume | Per hour (UK) | Per usage (UK) | Per month (UK) | Per hour (US) |
|---|---|---|---|---|---|---|
| Electric blanket | 70 W | per hour on the highest setting | 1.8p | 1.8p | 55.4p | 1.3 cents |
Rates: Ofgem cap 1 July to 30 September 2026 at 26.11p per kWh (source), EIA residential average June 2026 at 18.34 cents per kWh (source). Checked 2026-09-22.
Working it out yourself
Divide the watts on the control unit by a thousand, multiply by the hours, then multiply by your unit rate in pence.
A 70 watt blanket is 0.07 kilowatts. Run it for one hour and that is 0.07 kilowatt hours, which at 26.11p is 1.8p. Run it for eight hours and it is 0.56 kilowatt hours, or 14.6p, though in practice the thermostat cuts in and out once the bed is warm so the real figure lands nearer the setting one row.
Across a full heating season of 180 nights, preheating on high for half an hour and then dropping to setting one, a single blanket costs about £11.52. That is the whole year, not the month.
Five habits that make the difference
- Preheat for half an hour before bed and then drop to the lowest comfortable setting, which is how the blanket was designed to be used and where almost all of the saving lives.
- Use the timer if your control has one. A bed that is warm at 11pm does not need heating at 3am, because your body and the duvet take over.
- Put the blanket under a mattress protector rather than directly under the sheet, since the extra layer holds the heat in and lets you run a setting lower.
- Turn the thermostat for the bedroom down once the blanket is in use. A bedroom at 16 degrees with a warm bed is more comfortable than one at 20 degrees with a cold one, and the saving on the boiler dwarfs the blanket's entire running cost.
- Replace anything over ten years old. Old blankets lack the thermostat and the overheat protection of current ones, they run hotter for longer, and the fire services check them for a reason.
Against the other ways to stay warm in bed
Put the options side by side for one night and the ranking is clear. The blanket on low costs 5.9p. A hot water bottle filled from a kettle costs about 4.4p and goes cold by the small hours. A heated throw pulled over the duvet costs about the same as the blanket. An oil filled radiator in the bedroom costs £4.18 and dries the air out. Gas central heating left on overnight warms the whole house so that one person can be warm in one bed, which is the most expensive way to solve the problem by any measure.
There is one honest caveat. A blanket warms a person, not a building, so in a house that drops below about 14 degrees you still need background heat to look after pipes, plaster and anybody with a chest condition. The blanket lets you set that background level lower, it does not let you switch it off.
Why the box figure overstates it
Every electric blanket cycles. The element warms the bed to the temperature the setting asks for, the thermostat cuts the power, and it comes back on when the heat leaks away through the duvet. The rated wattage only applies during the on part of that cycle, which is most of the first twenty minutes and a diminishing share of every hour after.
That is why a 70 watt blanket measured over a whole night averages nearer 28 watts, and why the honest cost of a night is the low setting row rather than the full rating row. It also explains the gap between the figures on different websites, because a page that multiplies the rating by eight hours will always produce a number two or three times too large.
If you want your own figure, a plug in energy monitor left on the blanket overnight reads kilowatt hours rather than watts, and one night of data settles it.
What it costs in the United States
At the EIA residential average of 18.34 cents per kilowatt hour, an hour on a 70 watt blanket costs 1.3 cents and an eight hour night on the low setting costs 4.1 cents. A full winter of nightly use, 180 nights, comes to $8.09. In California at nearly 35 cents the same winter costs $15.32, and it is still cheaper than one evening of running a space heater in the bedroom.
Common questions
Do electric blankets use a lot of electricity?
No. A blanket heats the thirty or so litres of air between you and the mattress rather than the thirty thousand litres in the room, so it needs about a fortieth of the power of a heater. A full night on a low setting costs under 6p, which is less than boiling a kettle twice.
How much does it cost to run a queen or king size electric blanket?
A king size draws up to 90 watts on its highest setting, which is 2.3p an hour and 18.8p for an eight hour night if you leave it on high all the way through. Most people preheat on high and then drop to setting one, which costs closer to 6p a night.
Is it cheaper to use an electric blanket than central heating?
For sleeping, yes, and by an enormous margin. Heating a bedroom overnight with a 2 kilowatt heater costs £4.18, while the blanket costs 5.9p. The blanket does not keep the room above freezing though, so in a genuinely cold house you still want background heat for the plumbing and the plaster.
Is it cheaper to use an electric blanket or a hot water bottle?
They are close enough that comfort should decide it. Boiling enough water for a two litre bottle uses about 0.17 kilowatt hours and costs 4.4p, against 5.9p for a blanket left on low all night. The blanket is still warm at 4am and the bottle is not.