An electric blanket costs a small fraction of any heater to run. The Carmen double under-blanket is rated at 70W, so an hour on full heat costs 1.8p at the October 2026 price cap of 26.32p per kWh. The smallest whole-room heater we rate, Russell Hobbs’ 650W oil-filled radiator, costs 17.1p an hour, and a 2kW fan heater costs 52.6p.
Over a winter of four hours a night for 150 nights, at full rated power, that comes to £11.05 for the blanket, £102.65 for the oil radiator and £315.84 for the fan heater. The blanket is also the cheapest to buy, at £19.99 on Amazon UK today. There is no pence-back point to work out: it wins on both counts.
The verdict, 28 September 2026
- Per hour at full power: 1.8p for a 70W under-blanket, 17.1p for a 650W oil-filled radiator, 52.6p for a 2kW fan heater.
- Warming the bed for 30 minutes before you get in costs 0.9p with the blanket and 26.3p with a 2kW fan heater.
- A winter of four hours a night, 150 nights: £11.05, £102.65 and £315.84.
- The oil radiator costs 9.3 times as much per hour as the blanket. The fan heater costs 28.6 times as much.
- The two do different jobs. A blanket warms you in bed and does nothing for the room. A heater warms the air, and most of that heat is lost again when it goes off.
| Carmen under-blanket, 70W | Russell Hobbs oil radiator, 650W | 2kW fan heater | |
|---|---|---|---|
| 30 minutes | 0.9p | 8.6p | 26.3p |
| 1 hour | 1.8p | 17.1p | 52.6p |
| 4-hour night | 7.4p | 68.4p | £2.11 |
| 8-hour night | 14.7p | £1.37 | £4.21 |
| Winter, 4 hours × 150 nights | £11.05 | £102.65 | £315.84 |
| Price, 28 Sep 2026 | £19.99 | £28.99 | Varies |
Why the gap is so wide
A heater has to warm the air in a room, and the walls and furniture soak that heat up as fast as it can put it out. An electric blanket only has to warm a mattress and the person on it, under a duvet that holds the heat in. That is why a 70W blanket can do a job that would take a heater several hundred watts to do in the same room.
It is also why the comparison only holds in bed. A blanket will not take the chill off a bedroom while you get changed, and it does nothing for a room you are sitting up in. For that, a heated throw on the sofa is the nearer match: our electric blanket and heated throw guide prices both.
The heater figures are a ceiling
Every cost above assumes the appliance runs at full power the whole time. A heater with a thermostat switches off once the room reaches the set temperature, and an oil-filled radiator keeps giving off heat for a while after its element cuts out. Our appliance running cost calculator lets you set how much of the time each one is actually drawing power. At 60% of the time, the 2kW heater’s four-hour evening falls from £2.11 to £1.26.
Blankets cycle too. Most have several heat settings, and people often switch to low or off once the bed is warm. Even so, the blanket at full power all night costs less than 30 minutes of a 2kW fan heater.
Which one to use
If the goal is a warm bed, use the blanket and leave the heater off. Pre-warming for half an hour costs under a penny, and a whole winter of four-hour nights at full heat is about £11.
If you need the bedroom itself warm, use the oil-filled radiator on its thermostat and close the door. At 650W it is the cheapest whole-room heater in our electric heater rankings, and it costs a third as much per hour as a 2kW fan heater. If you have gas central heating, bear in mind that a kWh of heat from any plug-in heater costs 26.32p at the October cap, against about 8.9p from a 90% efficient gas boiler. Our UK running cost index sets out both.
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 wattage on each product’s Amazon UK listing: 70W for the Carmen double under-blanket and 650W for the Russell Hobbs oil-filled radiator. The 2kW figure is the most common rating for a plug-in fan heater and is not tied to one model. |
| Cost | Watts × hours ÷ 1,000 × 26.32p, at full rated power the whole time. |
| A winter | 150 nights of four hours. |
| Prices | Amazon UK, read 28 September 2026. They move often. |
| The pence-back point | Not needed here. The blanket is cheaper to buy and cheaper every hour it runs. |
What this comparison could not check
- We have not run any of these on a meter. Every cost uses the maker’s rated power for the full time, the most each could cost.
- How long a thermostat keeps a heater switched on, which depends on your room and the setting.
- Comfort. Whether a warm bed in a cold room suits you is something only you can judge.
The two we priced
Carmen Double Heated Under Blanket, 70W
£19.99. 1.8p an hour on full heat at the October 2026 cap, from its 70W rating, and 7.4p for a four-hour night. Carmen lists overheat protection.
The catch: It measures 120 × 107 cm, smaller than a double mattress, so check it covers the side you sleep on.
See it on AmazonRussell Hobbs 650W Oil Filled Radiator, 5 fin
£28.99. 17.1p an hour at full power, the lowest of the whole-room heaters in our rankings. It has a thermostat, and the oil keeps giving off heat after the element switches off.
The catch: At 650W it warms a small room slowly. There is no timer, so it has to be switched off by hand or on a plug timer.
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 electric blanket cheaper than a heater?
Much cheaper. At the October 2026 cap of 26.32p per kWh, a 70W electric under-blanket costs 1.8p an hour on full heat. A 650W oil-filled radiator costs 17.1p an hour and a 2kW fan heater 52.6p. The blanket warms the bed, not the room.
How much does an electric blanket cost to run per night?
A 70W blanket on full heat costs 7.4p for four hours and 14.7p for eight hours at 26.32p per kWh. Using it only to warm the bed for 30 minutes costs 0.9p.
How much electricity does a heater use compared with an electric blanket?
A 2kW fan heater uses 2 kWh an hour at full power, 28.6 times as much as a 70W electric blanket at 0.07 kWh. A 650W oil-filled radiator uses 0.65 kWh an hour, 9.3 times as much.
Is it cheaper to use an electric blanket than central heating?
For warming a bed, yes. A 70W blanket costs 1.8p an hour. Central heating warms the whole house, and its cost depends on your home and boiler, so the fair comparison is with the heating you would otherwise leave on overnight.
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Sources
- Ofgem, energy price cap unit rates and standing charges (1 October to 31 December 2026)
- Amazon UK listings for the Carmen Double Heated Under Blanket (B0CHS28R48) and Russell Hobbs 650W Oil Filled Radiator (B08BCRYWHG), wattage and prices read 28 September 2026