Sealy Posture Balance King Size 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
£827.10
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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
- Real space for two: At 75cm each for two people sharing, you can both turn over without negotiating for territory.
- Wider than a double: The UK king is 15cm wider than the UK double, which means fewer accidental elbows and less disturbance when one of you shifts.
- Extra length for taller sleepers: The UK king is 10cm longer than the UK double, so anyone approaching 6ft stops sleeping with their feet at the edge.
- Different schedules, less waking: If one of you gets up hours before the other, the wider footprint softens the movement that would wake a partner in a smaller bed.
- Room for the dog: When a pet claims the foot of the bed every night, the king's extra width means you still get your share.
This size suits you if...
You share the bed every night and a double has started to feel cramped, especially if one of you rises early and the other sleeps on. It also suits couples where one partner is approaching 6ft, since the 200cm length gives their feet room a standard double doesn't, or households where a dog or a child regularly joins you and you need the width to absorb it.
Consider another size if...
Your bedroom is smaller than the 2.7m x 2.9m we suggest for a UK king, or you sleep alone. We'd recommend the UK double of this mattress instead, which needs at least 2.6m x 2.8m.
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FAQ's
How big is the Sealy Posture Balance in a UK king?
It measures 150 x 200cm, which is 5ft x 6ft 6in. That works out at 75cm each for two people sharing, comfortably more personal space than a double offers. The 200cm length also matters: it's 10cm longer than a UK double, which taller sleepers feel every night.
Will a king size Sealy Posture Balance fit my bedroom?
We suggest allowing at least 2.7m x 2.9m for a UK king, which leaves room to walk round the bed and open drawers. New build master bedrooms can be tighter than they look once wardrobes go in, so measure the floor space that's actually left before committing to this size.
Is the UK king Sealy Posture Balance long enough for someone over 6ft?
At 200cm it's one of the longer standard UK sizes, and the UK king is 10cm longer than the UK double. For a sleeper approaching or over 6ft, that length is often the real upgrade rather than the width. Going up to the UK super king adds width only; it's the same length.
Should I choose the UK king or the UK super king?
The UK king is 30cm narrower than the UK super king, and the two are the same length. If your room meets the 3m x 2.9m we suggest for a UK super king and you want maximum space apart, size up. If width is adequate but the room is tighter, the UK king is the sensible pick.
Where can I find the best price on this size?
Prices change often, so the most reliable approach is to compare the retailers listed on this page, where prices are updated as retailers change them. Sealy publishes limited firmness and materials detail for the Posture Balance, so check the retailer's own listing for construction information before you buy.