A warm bed is especially welcome when the bedroom feels chilly. An electric underblanket lies on the mattress beneath your sheet, but the right one depends on more than the bed-size label: some warm just the middle, while others fit much farther down the mattress.
We’ve chosen six underblankets with different fits and controls, including compact double and king options and a deep fitted single. For a wider comparison that includes an overblanket, see our best electric blankets guide. Our buying guide explains the different types.
Our top 6 picks
Comparison at a glance
The most useful differences here are how much of the mattress the blanket covers, how it stays in place and whether each sleeper can choose a separate setting.
| Underblanket | Best for | Stated size | Controls and fit |
|---|---|---|---|
| Slumberdown Sleepy Nights King | Best straightforward king underblanket | 150 × 142cm | Three heat settings; Elasticated straps |
| Beurer TS 15 Double | Best simple double with one control | 152 × 122cm | One control; three settings; Mattress straps |
| Morphy Richards EverCosy Double | Best for a selectable timer | 150 × 122cm | One control; nine settings; 1–9-hour timer; Underblanket on mattress |
| Russell Hobbs RHEKB6003 King | Best longer king underblanket with two controls | 150 × 200cm | Two detachable controls; three settings; King bed; fitting method needs checking |
| Dreamland Cosy Dreamer King | Best cotton-feel king with independent sides | 160 × 152cm | Two digital controls; six settings; 1, 3 or 9-hour timer; Non-slip underside |
| Homefront Premium Fleece Single | Best deep fitted single with body-and-feet settings | 203 × 107cm; 20–40cm skirt depth | One control; separate body/feet settings; Deep elasticated skirt |
On a phone, swipe across the comparison. Match the actual dimensions—not just “double” or “king”—to your mattress.
The six best electric underblankets
Best straightforward king underblanket
1. Slumberdown Sleepy Nights King
The Sleepy Nights warms a smaller area than a full king mattress. That can work well when you want to take the chill off the middle of the bed without paying for a deeper fitted topper. The controls are simple, and the blanket can be washed once its controller is removed as instructed.
At a glance: King variant; 150 × 142cm; three heat settings; straps; detachable controller included.
What to check: The fabric does not run the full length of a king mattress. Check the exact pack and manual for the number of controllers before buying for two sleepers.
Other sizes: Available in single, small double, double and super king sizes. Sleepy Nights has one controller at every size; check the fabric measurements for the size you choose.
Choose it if
You want a simple king-bed warmer and do not need edge-to-edge coverage.
Skip it if
You want each side independently controlled or a full-length fitted cover.
Best simple double with one control
2. Beurer TS 15 Double
The TS 15 keeps things uncomplicated: one sliding control, three settings and straps that hold the underblanket on the mattress. Beurer specifies a 30°C wash after removing the control. Its heated area is shorter than a double mattress, so it is best thought of as a central bed warmer.
At a glance: Double variant; 152 × 122cm; one removable control included; three heat settings; straps.
What to check: Beurer lists a safety switch-off, not a user-set timer. Check the instructions if you need a timed finish.
Other sizes: Available as a TS 15 single. Check that variant’s dimensions and controls rather than assuming they match this double.
Choose it if
You sleep alone or are happy for one setting to warm the central part of a double bed.
Skip it if
Two sleepers need separate temperatures or you want a timer.
Best for a selectable timer
3. Morphy Richards EverCosy Double
The EverCosy gives you more choice than a basic three-setting blanket, with a timer you can set for the evening. The 150cm length means it warms part of a double bed rather than acting as a full-length topper. Its single detachable control suits one person or a couple content with the same setting.
At a glance: Double model 600121; 150 × 122cm; one detachable control included; nine settings and a 1–9-hour timer.
What to check: The timer is not the same as a fault-protection cut-off. Check the supplied manual for the exact settings and wash instructions.
Other sizes: The standard EverCosy underblanket also comes in single, king and super king sizes. The king model has two controls, unlike this double; check each size’s dimensions and controls.
Choose it if
You want to pre-warm a double bed and choose when the heat stops.
Skip it if
You need separate warmth on each side or a full-length cover.
Best longer king underblanket with two controls
4. Russell Hobbs RHEKB6003 King
At 200cm long, this king-size underblanket reaches farther down the bed than the shorter strapped picks. Two detachable controls let each sleeper choose a setting. It is a practical contrast to the compact Slumberdown, provided its fastening method suits your mattress.
At a glance: King model RHEKB6003; 150 × 200cm; two detachable controls included; three settings; 120W stated rating.
What to check: The product title calls it fitted while the product details mention ties. Check the exact fittings shown with the current pack rather than assuming a deep skirt.
Other sizes: The same Russell Hobbs range also has single RHESB6001 and double RHEDB6002 models. They differ in dimensions and power, so choose by the exact model number.
Choose it if
You share a king bed and want a longer warmed area with separate controls.
Skip it if
You need a confirmed deep fitted skirt or more heat and timer choices.
Best cotton-feel king with independent sides
5. Dreamland Cosy Dreamer King
The Cosy Dreamer is a softer cotton-finish option for a king bed shared by two people. Each side has its own digital controller and timer choices. Its 160cm length is generous compared with a short central pad but still not the same as a 200cm mattress cover.
At a glance: King variant; 160 × 152cm; two detachable controls included; six settings per side; timer choices.
What to check: Check the fabric dimensions against where you sleep; do not assume the word king means the whole mattress is heated.
Other sizes: The Cosy Dreamer cotton mattress warmer also comes in single and double sizes. Check the chosen size’s dimensions and number of controls; this recommendation is for the king.
Choose it if
You want separate settings and a cotton-finish underblanket without a deep fitted skirt.
Skip it if
A full-length fitted cover matters more than the fabric finish.
Best deep fitted single with body-and-feet settings
6. Homefront Premium Fleece Single
This single underblanket wraps around the mattress with a deep skirt, which may be easier to keep in place than corner straps. Its separate body and feet settings are useful when your feet need more warmth than the rest of you. It is a different purchase from the king and double models above: check the stated measurements against your own bed.
At a glance: Single variant; 203 × 107cm stated; 20–40cm skirt depth; detachable controller included.
What to check: Confirm the mattress depth and where the control lead exits. The stated cover dimensions are not a promise that every centimetre is heated.
Other sizes: This Homefront Premium fully fitted range also comes in double, king and super king sizes. Check the skirt depth, measurements and number of controls for the size you need.
Choose it if
You need a deep fitted single and want to adjust feet separately.
Skip it if
You have a shallower mattress or only want a simple pre-heat control.
Which one should you choose?
For a simple king-bed warmer, start with the Slumberdown Sleepy Nights. If two people want independent settings across a longer king underblanket, compare the Russell Hobbs with the cotton-finish Dreamland; their dimensions and fitting methods differ. On a double bed, the Beurer keeps controls simple while the Morphy Richards adds a timer. The Homefront is the pick for a deep single mattress, not a substitute for a double.
What to check before buying
How we chose
We checked six exact, currently available UK variants and compared their stated fabric dimensions, bed fit, control options, timer options and care information. Their product images and purchase destinations were checked against those variants. These are editorial selections based on manufacturer and retailer information, not hands-on tests; we have not measured warmth, comfort or running costs ourselves. Stock and product details can change.
Frequently asked questions
Is an electric underblanket the same as a heated throw?
No. An underblanket is made to lie flat on the mattress beneath the sleeper, as its instructions specify. A heated throw is generally made to use over you while sitting. Do not swap their intended positions.
Does a king-size label mean the whole bed is heated?
No. Compare the blanket’s actual length and width with your mattress. Some king models warm the central sleeping area; others cover much more of the bed.
Do all double and king underblankets have dual controls?
No. Check the exact size and variant. Some have one control, while others let each side choose its own setting.
Can I use an underblanket overnight?
Follow the exact product instructions. Electrical Safety First advises switching it off before sleep or using a model with automatic shut-off if it remains on overnight.
Can I wash an electric underblanket?
Only as its instructions allow. Detach the controller as directed and make sure the blanket and connector are completely dry before reconnecting.
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