Sealy Posture Balance 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
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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
- The classic shared size: At 135cm wide, two people sharing get 67.5cm each, enough for most couples who sleep reasonably close.
- Fits typical UK bedrooms: We suggest a room of at least 2.6m x 2.8m, which most British master bedrooms and many second bedrooms clear.
- Room for bedside tables: Because the UK double is 15cm narrower than the UK king, you're more likely to keep a bedside table on both sides in a modest room.
- Easy to dress: Standard double sheets and a 200 x 200cm duvet are stocked everywhere, so replacing bedding never becomes a hunt.
- Generous for one: A solo sleeper gets the full 135cm to spread out, with space to spare even if a dog or cat claims a corner.
This size suits you if...
You share the bed every night and your room sits around the typical UK size, or you sleep alone and want proper space to stretch without giving the whole room over to the bed. It also makes sense for a guest room that hosts visiting couples, or a first flat where the bed has to leave space for a wardrobe and drawers.
Consider another size if...
You and your partner both like space and your room can take a bigger bed. The UK king is 15cm wider and 10cm longer; we suggest at least 2.7m x 2.9m of floor space for it.
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FAQ's
Is the Sealy Posture Balance UK double big enough for a couple?
For most couples, yes. At 135cm wide it gives 67.5cm each for two people sharing, the width British couples have slept on for generations. If one of you is broad shouldered or a restless sleeper, the extra 15cm of the UK king is noticeable, provided your room allows at least 2.7m x 2.9m.
What room size do I need for the Sealy Posture Balance double?
We suggest at least 2.6m x 2.8m, which is our own guidance rather than Sealy's. That leaves walking space either side and room for a wardrobe or chest of drawers, so it works in most UK master bedrooms and plenty of second bedrooms or first flats.
Should I get the Sealy Posture Balance in a double or a small double?
The UK double is 15cm wider than the UK small double, and they're the same length. For a couple, that width matters and we'd lean towards the UK double. The UK small double suits a tighter room, where we suggest at least 2.4m x 2.8m.
Will a double mattress fit up the stairs in an older house?
Usually, yes. At 135 x 190cm the UK double is the size delivery teams handle most often, and it turns tight landings and terraced staircases more easily than a UK king. Measure your narrowest turn before ordering, especially in older properties, and check how the retailer delivers this model.
Is the UK double a good size for a guest room?
It's the standard choice. Visiting couples can share it comfortably, a solo guest gets plenty of space, and it fits alongside other furniture in rooms that meet our suggested 2.6m x 2.8m minimum. Guest bedding is simple too: double sheets and a 200 x 200cm duvet are sold everywhere.