Sealy Posture Balance Small Double Mattress
The Sealy Posture Balance comes in five UK sizes, from Single up to Super King.
- Firm feel with cushioned comfort
- Open-cell foam for breathability
- Hypoallergenic fibre fillings
£737.10
Get the lowest price we've found
Save with the previous model
Some retailers still sell the earlier version of this mattress for less than the current model's best price.
Sealy Posture Balance Mattress
More available sizes
Mattress details
Mattress
Sealy Posture Balance Mattress
Size
Firmness
Firm
Construction
Depth (cm)
Layers
3
Layer Details
PostureTech 2.0 pocket springs
Pocket springs made with higher gauge wire sit at the heart of this firmer design. They give the mattress its supportive base feel, which suits sleepers who like a firm, steady surface.
MicroCell
An open-cell foam that is durable and resilient, with a soft feel. The open structure helps air move through, so it should sleep less warm than a dense foam.
OptiForm firm foam
A double layer of firm foam that gently cushions and adapts to your body. It adds some give on top of the firm feel, so the surface isn't hard.
Layer details from mattressman.co.uk product page, October 2026.
Key benefits
- Real space for one: At 30cm wider than the UK single, a solo sleeper can starfish, roll and change position without meeting the edge.
- Fits compact rooms: It's 15cm narrower than the UK double, which can be the difference between a door that clears the bed and one that doesn't.
- Room to walk around: Allow at least 2.4m x 2.8m and you keep usable floor space on both sides, rather than shuffling past the footboard.
- Standard 4ft bedding: Small double fitted sheets are widely stocked, and a standard double duvet drapes generously over the 120cm width.
- Handles the occasional guest: Two people can share for a weekend visit comfortably enough, making it a sensible pick for a guest room or holiday let.
This size suits you if...
You sleep alone but have outgrown a single, perhaps a teenager whose room can't lose any more floor space, or your bedroom is a box room, loft conversion or studio where the 15cm saved over a UK double keeps a walkway clear. It also suits a guest room or small second bedroom in a rental, where couples stay occasionally but nobody sleeps there every night.
Consider another size if...
You share the bed most nights, or you're a taller sleeper wanting extra length. We'd recommend the UK double instead, which is 15cm wider and the same length; allow at least 2.6m x 2.8m of room for it.
Similar Mattresses in This Price Range
Did you know? On Mattress Unboxed we have over 1,000 different mattresses to suit all types of sleepers. View all mattresses.
FAQ's
Is a small double Sealy Posture Balance big enough for two adults?
For occasional nights, yes. At 120cm wide it gives a couple 15cm less width than a UK double, which is fine for a weekend stay but a squeeze every night. If you share regularly, the UK double version of this mattress is the better buy, provided your room offers at least 2.6m x 2.8m.
What room size do I need for the Sealy Posture Balance small double?
We suggest at least 2.4m x 2.8m. That's our guidance rather than Sealy's, and it leaves enough clearance to open the door, walk down one side and fit a wardrobe or chest of drawers without the room feeling cramped. In a loft conversion, check the sloping ceiling leaves headroom beside the bed too.
How much bigger is a small double than a single?
The UK small double is 30cm wider than the UK single, and the two are the same length at 190cm. That extra width is the whole point of the size: an adult or older teenager gets proper turning room while the bed's footprint grows far less than moving to a UK double or UK king would.
What bedding fits the Sealy Posture Balance in a small double?
You need small double, sometimes labelled 4ft, fitted sheets to match the 120 x 190cm mattress. A standard double duvet works well on top, with a slightly more generous overhang than it gives on a UK double. Both are easy to find from mainstream UK bedding retailers.
Would the small double or the UK king suit a taller sleeper better?
The UK king, if your room allows it. The UK small double is 10cm shorter and 30cm narrower than the UK king, and that extra length matters once you're around six foot tall. We suggest at least 2.7m x 2.9m of room for the UK king, so measure before you decide.