Silentnight Amsterdam Miracoil Ortho King Size Mattress
The Silentnight Amsterdam Miracoil Ortho is an orthopaedic mattress described on its Mattress Online listing as extra firm, so treat this as a properly solid feel rather than a middling firm.
- Properly firm, zoned support
- Fibres & cover help you sleep cool
- Made without chemical treatments
£244
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Silentnight Amsterdam Miracoil Ortho Mattress
More available sizes
Last seen for £534 at Mattress Online on 2nd September 2026
Mattress details
Mattress
Silentnight Amsterdam Miracoil Ortho Mattress
Size
Firmness
Firm
Construction
Orthopaedic
Open Coil Spring
Eco-Friendly
Depth (cm)
24
Layers
3
Layer Details
Damask cover
A finely woven, durable fabric that feels soft to the touch, which means the firmness underneath isn't harsh against your skin. It doesn't retain heat, so it helps keep the surface cool.
Eco Comfort Fibre
A layer of fibres made from recycled materials that gives cushioning comfort over the springs. It also helps evaporate body heat, which means a cooler night if you tend to run warm.
Miracoil Springs
Silentnight's own open coil system with separate support zones that support the spine and distribute your weight evenly. In practice, that means firmer support where you're heaviest and less pressure on hips and shoulders.
Layer details from mattressonline.co.uk product page, September 2026.
Key benefits
- 75cm of firm support each: Two people sharing get 75cm each, which means the Miracoil zones can support each of you where you're heaviest without either sleeper drifting into the middle.
- 15cm wider than a UK double: That 15cm is roughly a shoulder's worth of extra room, a difference you notice most on a firm mattress where you can't sink into your own dip.
- Extra length for taller sleepers: At 200cm, the UK king is 10cm longer than the UK double, so anyone approaching six foot stops sleeping with their feet at the frame.
- More space, less disturbance: An open coil system does transfer some movement, so the added width helps here: the further apart you sleep, the less you feel a partner getting up early.
- A cool surface at any width: The Eco Comfort Fibre layer helps evaporate body heat across the full 150cm, useful when two people share and the bed warms up faster.
This size suits you if...
You share the bed every night and both want firm orthopaedic support with more personal space than a double allows, one of you is around six foot and needs the 200cm length, or your schedules differ and you'd rather an early alarm didn't wake you both. Allow at least 2.7m x 2.9m of floor space and the UK king fits comfortably.
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 instead, which suits rooms of at least 2.6m x 2.8m.
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FAQ's
How big is the Silentnight Amsterdam in a UK king?
The UK king measures 150 x 200cm, which is 5ft x 6ft 6in. Two people sharing get 75cm of width each. The mattress itself is 24cm deep in every size, so it's the footprint that changes here, and you'll need king sheets rather than double ones.
Is a UK king Silentnight Amsterdam good for couples?
For couples who both want a firm feel, yes. The Miracoil springs are zoned, so each of you gets support matched to where your weight sits. One caveat: open coil systems pass on more movement than pocket springs, so the UK king's extra width does some of the work of keeping a restless partner's movements away from you.
What size room do I need for the king size Silentnight Amsterdam?
We suggest a room of at least 2.7m x 2.9m for a UK king, which leaves enough space to walk around the bed and open drawers. That's our guidance rather than Silentnight's. In a new build master bedroom, measure with the wardrobes in place; these rooms are often tighter than they first appear.
Should I choose the Silentnight Amsterdam in a UK king or super king?
The UK king is 30cm narrower than the UK super king; both are the same 200cm length. If your priority is length for a taller sleeper, the UK king already delivers it. Go for the UK super king only if you have a room of at least 3m x 2.9m and want the maximum width between you.
Is the UK king Silentnight Amsterdam long enough for tall sleepers?
At 200cm, it's 10cm longer than the UK double, and on a firm orthopaedic mattress that matters: feet hanging over the end of an unyielding surface is more uncomfortable than on a softer one. Most sleepers up to around six foot four will find the length comfortable.