MattressNextDay Super Firm Foam Mattress
Mattress
MattressNextDay Super Firm Foam Mattress
Size
Firmness
Firm
Construction
Depth (cm)
20
Layers
Layer Details
- Deep Reflex Foam. Deep reflex foam gently contours your body without compromising the extra firm feel, which means you get personalised pressure relief across your entire body while the surface stays supportive. Reflex foam is denser and springier than standard memory foam, so you won't feel stuck in one position.
Layer details from mattressnextday.co.uk product page, September 2026.
- 75cm each for two sharing: You each get 75cm of width, which means you can settle into your own position on this extra firm surface without negotiating for space.
- Extra length for taller sleepers: At 200cm long, the UK king suits anyone approaching six foot who finds standard-length mattresses leave their feet at the edge.
- Firm support across the full width: The deep reflex foam keeps its extra firm feel edge to edge, so back and front sleepers get real resistance wherever they end up lying.
- More distance on different schedules: When one of you leaves for work early, the extra width means less shuffling past a sleeping partner and fewer disturbed mornings.
- Manageable at 20cm deep: An all-foam build at this depth is easier to manoeuvre up a staircase than a deep sprung king, which helps in tighter homes.
This size suits you if...
You share the bed every night and have found a double too snug, you want a genuinely hard surface under both of you rather than one that softens where the heavier partner lies, or one of you is approaching six foot and needs the 200cm length. It also suits couples on mismatched schedules who want enough width to come and go without waking each other.
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. In either case we'd recommend the UK double instead, allowing at least 2.6m x 2.8m for it.
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How big is the MattressNextDay Super Firm mattress in a UK king?
It measures 150 x 200cm, or 5ft x 6ft 6in. Depth is 20cm, which is slightly slimmer than some, though an all-foam build has no springs to house. Two people sharing get 75cm of width each, a comfortable amount for couples who want their own space on a firm surface.
Is the UK king big enough for a couple who like their own space?
Yes, and it's the size most couples upgrade to for exactly that reason. You get 75cm each for two people sharing, and the extra firm surface means you lie on the mattress rather than sinking into it, so neither of you rolls towards the middle when the other moves.
Should I get this mattress in a UK double or a UK king?
The UK king is 15cm wider and 10cm longer than the UK double. The UK double gives 67.5cm each for two sharing, so the UK king gives 7.5cm more each. If either of you is tall, or you keep waking each other, the UK king is the safer choice, room size permitting.
Is this firm mattress long enough for someone over six foot?
At 200cm, the UK king is 10cm longer than the UK double or UK single, which is a real difference if you're around six foot or above. Your feet stay on the mattress rather than hanging past the end, and on an extra firm surface you'll notice full-length support more than on a softer one.
What room size does the Super Firm mattress need in a UK king?
We suggest a room of at least 2.7m x 2.9m, with 3.2m x 3.2m feeling comfortable. That leaves walking space on both sides, useful for couples on different schedules. New build master bedrooms can shrink quickly once wardrobes go in, so measure the usable floor space rather than trusting the floor plan.