Sealy Alford Advantage King Size Mattress
The Sealy Alford Advantage is a firm mattress pairing PostureTech Core Support Springs with Soft White Fibres that cushion pressure points like your hips and shoulders.
- Firm feel with no sinking sensation
- Targeted support where you need it
- Fibre top softens hips & shoulders
£398
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 Alford Advantage Mattress
More available sizes
Mattress details
Mattress
Sealy Alford Advantage Mattress
Size
Firmness
Firm
Construction
Depth (cm)
24
Layers
2
Layer Details
Comfort Layer
Soft White Fibres sit at the surface to cushion the hardest parts of your body, such as your hips and shoulders. They take the edge off the firm feel rather than adding plush depth.
Support System
PostureTech Core Support Springs form the core, using unique shapes and varied tension across the unit. In practice that means full-body support with pressure relief where you carry the most weight.
Layer details from mattressonline.co.uk product page, September 2026.
Key benefits
- Real space for two: At 75cm each for two people sharing, you can change position without negotiating for territory.
- Length for taller sleepers: The UK king is 10cm longer than the UK double, welcome breathing room for anyone approaching six foot.
- A firm surface that stays put: The varied-tension springs hold their shape under weight, which means less movement transferring across the bed when one of you gets up early.
- Fits most main bedrooms: We suggest a room of at least 2.7m x 2.9m, which most UK master bedrooms can manage.
- Simple build, sensible price: The Soft White Fibre comfort layer keeps things basic, and in a larger size that restraint keeps the cost accessible.
This size suits you if...
You share the bed every night and a double has started to feel cramped, especially if one of you sleeps on your back or front and wants firm support. It's also a strong pick if either partner is tall, since the extra 10cm of length over the UK double stops feet hanging off the end, or if a pet routinely claims a corner of the duvet.
Consider another size if...
Your bedroom falls short of the 2.7m x 2.9m we suggest for a UK king, or you sleep alone. We'd recommend the UK double instead, which needs at least 2.6m x 2.8m of floor space.
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 the Sealy Alford Advantage in a UK king good for couples?
Yes, provided you both like a firm feel. The 150cm width gives 75cm each for two people sharing, and the PostureTech Core Support Springs use varied tensions across the unit, so each of you gets support where you carry the most weight. Lightweight side sleepers may still find the surface a little unyielding on shoulders and hips.
Will a firm mattress like this reduce partner disturbance in a king?
It helps on two fronts. The extra width over a double means fewer accidental collisions, and a firm sprung surface tends to transfer less movement than a soft one, so an early alarm on one side is less likely to wake the other. If your schedules rarely match, the UK king is the sensible minimum for sharing.
Is the UK king version long enough for someone over six foot?
At 200cm, or 6ft 6in, the UK king is 10cm longer than the UK double, and for taller sleepers that length is often the real upgrade rather than the width. Most people over six foot will fit comfortably; if you're exceptionally tall, check the gap between your height and 200cm before deciding.
Should I choose the UK king or UK super king Sealy Alford Advantage?
The UK super king is 30cm wider than the UK king, and the two are the same length, so the question is width and room size. We suggest at least 3m x 2.9m for the UK super king, against 2.7m x 2.9m for the UK king. If a dog or child regularly joins you, that extra 30cm is genuinely useful.
What room size do I need for this mattress in a UK king?
We suggest at least 2.7m x 2.9m, with more feeling comfortable once wardrobes and drawers go in. New build master bedrooms can be tighter than the plans suggest, so measure the floor with furniture in place, and check you can still open doors and walk both sides of the bed.