# What size electric blanket do I need? Sheet 09 · Heating and damp, whichfits.uk. A Markdown copy of https://whichfits.uk/electric-blanket-size. The page itself has the working form and the Amazon.co.uk links: link to the page, not to this copy. 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. ## Work it out Worked example, with the inputs the sheet opens on: - Bed size: Double (135 × 190 cm) - Under or over: Underblanket: goes under the sheet, warms the bed before you get in **Double underblanket** 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.uk ## Under 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. ## The 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. ## Dual 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. ## The 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. ## Where to get it - Get a single fitted electric underblanket on Amazon.co.uk. For a 90 cm mattress. - Get a double electric underblanket (120 cm wide, fits a small double edge to edge) on Amazon.co.uk. The 120 cm bed, the one the shops forget. - Get a double fitted electric underblanket on Amazon.co.uk. Two controls. See above. - Get a king size electric underblanket with dual controls on Amazon.co.uk - Get a super king electric underblanket on Amazon.co.uk - Get a heated throw, 130 × 180 cm on Amazon.co.uk. 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. ## Where the numbers come from 1. [UK bed and mattress size guide](https://bedadvice.co.uk/beds-and-beyond/bed-sizes-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) 2. [Winter Warmer electric blanket, sizes](https://www.silentnight.co.uk/silentnight-winter-warmer-electric-blanket.html), Silentnight. Single 72 × 135, double 120 × 135, king 137 × 165, super king 160 × 200 cm (read 17 October 2026) 3. [Wonderfully Warm electric blanket, sizes](https://slumberdown.co.uk/products/wonderfully-warm-electric-blanket), Slumberdown. Single 80 × 150, double 120 × 150, king 150 × 160, super king 170 × 160 cm, with elasticated straps (read 17 October 2026) 4. [Underblankets (fitted, full bed size)](https://www.dreamlanduk.co.uk/collections/underblankets), 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. **Other sheets** - Sheet 08 [How much does this heater cost to run?](https://whichfits.uk/heater-running-cost) - Sheet 05 [What size electric heater do I need?](https://whichfits.uk/electric-heater-size) - Sheet 07 [What size dehumidifier do I need?](https://whichfits.uk/dehumidifier-size) --- whichfits.uk is written and published by Jaco Olwagen, with software doing the sums. Links to Amazon.co.uk earn the site a commission if you buy something, and that is how the lights stay on. Nothing here is bought, tested or handled: every number on every sheet comes from the documents named at the foot of that sheet, with the date they were read.