Sheet 09 · Heating and damp
What size electric blanket do I need?
Most electric blankets are cut smaller than the bed, which is the one fact that would have saved a lot of people a trip to the post office. A double underblanket from Silentnight is 120 wide by 135 long on a mattress of 135 by 190: it stops short of the edges so you cannot hang over the heated bit, and short of the pillow end so you are not sleeping on the controller. The fitted ones with elasticated corners are full size, and the box says which kind it is. A king blanket is wider than a double but barely longer, because beds in this country got wider before they got longer.
Pick the bed, pick under or over, and the sheet gives you the size name the shops use and what the makers say it measures. Measure the mattress if the bed came with the flat. ‘Double’ on the receipt means nothing until the tape measure agrees.
1Work it out
About 120 wide by 135 to 150 long, or 137 × 190 if it is a fitted one for a double mattress of 135 × 190 cm. An underblanket is cut smaller than the mattress on purpose: it stops short of the edges and the pillow end, where you would roll onto the controls.
Get a double fitted electric underblanket on Amazon.co.ukor search Amazon.co.uk for “double electric blanket dual control”
2Under or over
An underblanket goes between the mattress and the bottom sheet, warms the bed before you get in and, on the modern ones, keeps a low heat all night. It has ties or an elasticated skirt to stop it bunching. An overblanket goes on top of you, like a heated duvet; a heated throw is a smaller one for the sofa. If the question is ‘cold bed’, it is an underblanket. If the question is ‘cold me, on the settee’, it is a throw, whatever size the bed is.
3The UK sizes
A UK single mattress is 90 by 190 centimetres, a small double 120 by 190, a double 135 by 190, a king 150 by 200 and a super king 180 by 200, with the makers allowed two centimetres either way. Blanket makers cut to those, and the sheet shows what each size measures at Silentnight, Slumberdown and Dreamland. A European or an IKEA double is 140 by 200, a touch bigger both ways, and takes the UK double blanket with a little less to spare.
4Dual controls
From a double up, look for two controls. The person who likes it on 3 and the person who likes it off are both right, and a single control decides it for them every night. Below a double there is no second person to argue with.
5The old one
Electric blankets wear out. Scorch marks, a frayed flex, a controller that clicks or a smell of hot dust: bin it. The makers print a date of manufacture on the label and an age they stand behind, and a blanket past it goes whatever it looks like.
6Where to get it
- Get a single fitted electric underblanket on Amazon.co.ukor search Amazon.co.uk for “single electric blanket underblanket”For a 90 cm mattress.
- Get a double electric underblanket (120 cm wide, fits a small double edge to edge) on Amazon.co.ukor search Amazon.co.uk for “small double electric blanket”The 120 cm bed, the one the shops forget.
- Get a double fitted electric underblanket on Amazon.co.ukor search Amazon.co.uk for “double electric blanket dual control”Two controls. See above.
- Get a king size electric underblanket with dual controls on Amazon.co.ukor search Amazon.co.uk for “king size electric blanket dual control”
- Get a super king electric underblanket on Amazon.co.ukor search Amazon.co.uk for “super king electric blanket dual control”
- Get a heated throw, 130 × 180 cm on Amazon.co.ukor search Amazon.co.uk for “heated throw electric blanket”For the sofa, or over the duvet. One person’s worth, whatever the bed.
Those links go to Amazon.co.uk and earn this site a commission if you buy. The price is the same either way, and nothing on this sheet changes because of it.
7Where the numbers come from
- UK bed and mattress size guide, Bed Advice UK (National Bed Federation). Single 90 × 190, small double 120 × 190, double 135 × 190, king 150 × 200, super king 180 × 200 cm (read 17 October 2026)
- Winter Warmer electric blanket, sizes, Silentnight. Single 72 × 135, double 120 × 135, king 137 × 165, super king 160 × 200 cm (read 17 October 2026)
- Wonderfully Warm electric blanket, sizes, Slumberdown. Single 80 × 150, double 120 × 150, king 150 × 160, super king 170 × 160 cm, with elasticated straps (read 17 October 2026)
- Underblankets (fitted, full bed size), Dreamland. Single 90 × 190, double 137 × 190, king 150 × 200, super king 180 × 200 cm; heated throws 120 × 160 and 135 × 180 (read 17 October 2026)
Data on this sheet last changed 17 October 2026.