Sealy Duchess Contract Super King Mattress
The Sealy Duchess Contract is a medium firm sprung mattress with a quilted surface, available in UK Single, Double, King and Super King sizes.
- Suits most back & combination sleepers
- Usable space right to the edges
- 5-year guarantee
£999
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 Duchess Contract Mattress
More available sizes
Mattress details
Mattress
Sealy Duchess Contract Mattress
Size
Firmness
Medium Firm
Construction
Foam
Depth (cm)
26
Layers
4
Layer Details
Quilted Surface
A quilted sleep surface sits on top, which means a soft, slightly cushioned first impression when you lie down. It's a traditional finish rather than a plush pillow-top feel.
Sealy Medium Foam
Generous layers of Sealy medium foam add comfort between you and the springs. This is what softens the medium firm support so it doesn't feel hard at the surface.
PostureTech Core Support Springs
The PostureTech Core Support system uses springs that gradually get firmer as pressure increases, which means heavier areas like your hips get deeper support while lighter areas rest more gently. The result is pressure relief without sagging.
EdgeGuard
EdgeGuard reinforces the perimeter for added durability and edge-to-edge support. In practice, that gives you more usable sleeping space right up to the sides.
Layer details from sealy.co.uk product page, September 2026.
Key benefits
- 90cm each, every night: With 90cm each for two people sharing, a partner who fidgets or turns over frequently becomes far easier to sleep through, which matters more than any comfort layer.
- Room for company: When children pad through at 3am or the dog treats the bed as routine, a super king means everyone still gets a workable share.
- EdgeGuard across the full 6ft width: EdgeGuard reinforcement runs around the border, so both sleepers can use the outer edges without that rolling-off feeling, making the full 180cm genuinely usable.
- Progressive support at any sharing weight: The PostureTech Core Support springs firm up as you press into them, so two sleepers of different builds each get support suited to their own weight.
- Suits larger master bedrooms: In a period property or generous new build master, a UK king can look undersized; the extra 30cm of width fills the room properly.
This size suits you if...
You share the bed every night and want the most space a standard UK size offers, your children or pets regularly join you and a UK king has started to feel crowded, or your partner is a restless sleeper and you'd rather solve that with distance than with a different mattress. Your bedroom should measure at least 3m x 2.9m for it to work.
Consider another size if...
Your bedroom falls short of our suggested 3m x 2.9m minimum, or you sleep alone. The UK king is 30cm narrower and the same length, and we'd recommend it instead; allow at least 2.7m x 2.9m for that size.
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 super king Sealy Duchess Contract too big for my bedroom?
We suggest at least 3m x 2.9m of floor space for a UK super king, and that's before wardrobes and drawers. In a loft conversion, the slope often decides which wall the bed can sit against, so measure the usable head height too. If the room falls short, the UK king needs at least 2.7m x 2.9m.
Will two people turning the Duchess Contract super king be manageable?
This is a double-sided mattress that needs regular turning, and at 180 x 200cm it is a two-person job every time. If you can commit to flipping something this size, the double-sided design tends to reward you with more even wear over the years. If you can't, a smaller size or a no-turn design suits you better.
How much space does each person get on the super king Duchess Contract?
You get 90cm each for two people sharing, and because EdgeGuard reinforces the perimeter, that width is usable right up to the sides rather than tapering off. It also means a child climbing in at night doesn't force one adult onto a sagging edge.
Is the super king a good choice for a restless partner?
Yes, and it's the strongest reason to size up. Sheer distance does more to protect your sleep than any comfort layer, and 90cm each for two people sharing puts a fidgeting partner far enough away to ignore. The responsive sprung feel of the Duchess Contract transfers some movement, so the extra width earns its cost here.
Will the Sealy Duchess Contract super king fit up my stairs?
Sprung, double-sided mattresses like this don't fold or roll, so measure your staircase, landing turns and door swings before ordering. A 180 x 200cm mattress is awkward on a tight turn, and it's the check most likely to catch you out at this size. Compare the retailers listed on this page for delivery access details.