Double, King or Super King Heated Under Blanket: Sizing FAQ
By Home & Kitchen Appliances – Morphy Richards UK | Published: 2026-11-04
Category: ハウツーガイド
Work out which heated under blanket size fits your bed, how much overhang you need, and why a super king blanket suits some mattresses better than others.
Quick answer
Match the blanket to your mattress size, not your duvet: a double heated under blanket fits a double mattress, a king size electric under blanket fits a king, and a super king heated blanket fits a super king. If your mattress sits between sizes, size up rather than down.
Why mattress size beats duvet size for under blankets
Under blankets are designed to lie flat on top of the mattress and under the sheet, so the mattress dimensions are the only reliable guide. Duvet sizes vary between brands and can be larger than the mattress, which makes them a poor reference point. Check the mattress label or measure the width and length before ordering.
When a super king blanket is the safer choice
If your mattress is a true super king, a super king heated blanket gives full coverage without stretching. For mattresses that are slightly smaller but still large, a super king blanket can overhang, which may cause the edges to fold or bunch. A double heated under blanket is the better fit for a standard double mattress, while a king size electric under blanket suits a king mattress.
What premium fleece adds to fit and feel
A premium fleece under blanket sits smoothly under a sheet and adds a soft layer, but it does not change the sizing rules. The fleece surface can make the blanket slightly bulkier at the edges, so leave a little slack when tucking in. Always follow the manufacturer’s fitting instructions for your specific model.
Heated under blanket sizing questions answered
- Which size electric blanket do I need for a double bed?
- Choose a double heated under blanket. It is cut to match a double mattress, so it lies flat without hanging over the sides. Measure your mattress first; if it is a small double, check the blanket’s stated dimensions.
- Can I use a king size electric under blanket on a double bed?
- It will physically cover the mattress, but the excess material can bunch at the edges and may not sit safely under the sheet. A double size is the correct fit. Avoid sizing up unless your mattress is genuinely between sizes.
- Is a super king heated blanket too big for a king bed?
- Yes, it will overhang on a standard king mattress. Use a king size electric under blanket for a king bed, and reserve the super king for a super king mattress. If you are unsure, size down rather than up for under blankets.
- How much overhang is acceptable on a heated under blanket?
- A small amount of overhang at the foot or sides is usually fine if the blanket stays flat, but avoid folds or rucks that could trap heat. Follow the manufacturer’s guidance for your model. Never tuck an oversized blanket tightly under the mattress.
- Does a premium fleece under blanket fit differently?
- Premium fleece adds surface softness but does not change the mattress size it is designed for. The fleece can feel slightly thicker, so smooth it out before putting the sheet on. Fit by mattress size, not by the feel of the fleece.
Product facts
- EverCosy Super King Premium Fleece Heated Electric Under Blanket: Super king premium fleece heated electric under blanket with overheat protection and fast heating technology. The super king size covers a full super king mattress, and the safety cut-off adds peace of mind for overnight use.
EverCosy Super King Premium Fleece Heated Electric Under Blanket - EverCosy Double Premium Fleece Heated Electric Under Blanket: Double premium fleece heated electric under blanket with overheat protection and fast heating technology. A dedicated double size avoids the excess overhang you would get from putting a larger blanket on a double mattress.
EverCosy Double Premium Fleece Heated Electric Under Blanket
