Last seen for £395 at Mattress Man on 10th November 2026
Silentnight Memory 3 Sleep King Size Mattress
The Silentnight Memory 3 Sleep Mattress is a memory foam mattress from one of Britain's best-known bed brands.
- Medium feel for most sleepers
- Memory foam softens pressure points
- Fits UK & EU bed frames
Save with the previous model
Some retailers still sell the earlier version of this mattress for less than the current model's best price.
More available sizes
Last seen for £395 at Mattress Man on 10th November 2026
Last seen for £449 at Mattress Man on 10th November 2026
Last seen for £395 at Mattress Man on 10th November 2026
Last seen for £335 at Mattress Man on 10th November 2026
Last seen for £345 at Mattress Man on 10th November 2026
Last seen for £255 at Mattress Man on 10th November 2026
Last seen for £249 at Mattress Man on 10th November 2026
Mattress details
Mattress
Silentnight Memory 3 Sleep Mattress
Size
Firmness
Medium
Construction
Foam
Memory Foam
Depth (cm)
Layers
2
Layer Details
Foam layer (top)
The first of two foam layers in an 18 cm mattress. Together they give the medium feel, with memory foam that softens as it warms and gives your hips and shoulders a gentler landing.
Foam layer (base)
The second foam layer sits beneath the first. It is part of an all-foam build, so you get a steady, sprung-free feel rather than the bounce of a pocket spring mattress.
Layer details from mattressman.co.uk and robertdyas.co.uk product pages, October 2026.
Key benefits
- Real space for two: At 75cm each for two people sharing, you can both change position without a negotiation, which is the main reason couples move up to a UK king.
- Memory foam softens disturbance: Foam absorbs movement rather than transferring it, so if one of you leaves for work hours before the other, the sleeper left behind feels less of it.
- Extra length for taller sleepers: The UK king is 10cm longer than the UK double at 200cm, which is a genuine relief if either of you is approaching six foot.
- Affordable route to a bigger bed: This model sits at the budget end of memory foam from a major brand, so sizing up to a UK king stays realistic.
- Standard bedding, easy shopping: At 5ft x 6ft 6in this is the standard UK king, so ordinary king sheets and duvets fit without hunting for odd sizes.
This size suits you if...
You share the bed every night and a double has started to feel cramped, or one of you keeps unsocial hours and you want the width and motion-absorbing foam to keep disturbance down. It also suits couples where one partner is tall, since the 200cm length gives feet somewhere to go. If the dog treats the bed as its own, the extra width helps there too.
Consider another size if...
Your bedroom is smaller than the 2.7m x 2.9m we suggest for a UK king. In that case we'd recommend the UK double instead, which is 15cm narrower and needs a room of at least 2.6m x 2.8m.
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FAQ's
Is the Silentnight Memory 3 in a UK king big enough for a couple?
Yes, for most couples comfortably. At 150cm wide you each get 75cm of space, noticeably more than a double offers, and the memory foam moulds to each sleeper separately rather than tipping you towards the middle. If one of you is restless, that extra width plus the foam's movement absorption is the combination doing the work.
Will a UK king Silentnight Memory 3 fit in my bedroom?
We suggest a room of at least 2.7m x 2.9m for a UK king, with around 3.2m x 3.2m feeling comfortable. That's our guidance rather than Silentnight's. Measure with wardrobes and drawers in place, especially in a new build master bedroom, which can feel smaller than the floor plan suggests once furniture goes in.
Is the UK king long enough for someone over six foot?
At 200cm, the UK king is 10cm longer than the UK double, and that difference is exactly what taller sleepers notice. If either of you is approaching six foot and currently sleeps diagonally or with feet at the edge, the length is arguably a bigger upgrade than the width.
Should we choose the UK king or the UK super king?
The UK super king is 30cm wider than the UK king, and the two are the same length, so the choice is purely about width and room size. We suggest at least 3m x 2.9m for the UK super king. If your room can take it and you both spread out, size up; otherwise the UK king is the sensible middle ground.
Does the Silentnight Memory 3 king reduce partner disturbance?
It helps in two ways. Memory foam absorbs motion rather than bouncing it across the bed, so one partner getting up early transmits less movement. And 75cm of width each means you're less likely to be in contact in the first place. Silentnight doesn't publish detailed construction specs, so we can't quantify it beyond that.