Silentnight Miracoil Ortho King Size Mattress
The Silentnight Miracoil Ortho is a firm mattress built around Silentnight's zoned Miracoil® spring system, topped with breathable Eco Comfort fibres made partly from recycled plastic bottles.
- Firmer support under your hips
- Supports right to the edge
- 60-night trial & 5-year guarantee
£307.07
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Silentnight Miracoil Ortho Mattress
More available sizes
Mattress details
Mattress
Silentnight Miracoil Ortho Mattress
Size
Firmness
Firm
Construction
Open Coil Spring
Depth (cm)
24
Layers
2
Layer Details
Eco Comfort Fibres
A comfort layer made with Silentnight's Eco Comfort fibres, partially made from recycled plastic including bottles. It is breathable, helps regulate temperature and reduces moisture build-up, which means you should feel less clammy overnight.
Miracoil® springs
Silentnight's Miracoil® support system gives zoned support where your body needs it most, so heavier areas like your hips get firmer resistance. It also supports right to the edge of the bed and is designed to limit partner disturbance when one of you moves.
Layer details from silentnight.co.uk product page, September 2026.
Key benefits
- Space to sleep undisturbed: With 75cm each for two people sharing, you can shift position without nudging your partner, and the springs are designed to limit movement transfer between you.
- Edge-to-edge firm support: Silentnight says the Miracoil system supports right to the edge, which means those 150cm of width are all genuinely usable rather than a soft border you avoid.
- Length for taller sleepers: At 200cm, the UK king is 10cm longer than the UK double, a real relief if one of you is approaching six foot and forever hanging over the end.
- A big bed that stays cool: More shared body heat in a bigger bed can mean warmer nights, so the breathable Eco Comfort fibre layer helps you both feel less clammy.
- Firm support across the whole width: Zoned Miracoil springs give firmer resistance under your hips wherever you lie, useful when two sleepers of different weights share the same mattress.
This size suits you if...
You share the bed every night and a double has started to feel cramped, especially if you and your partner keep different hours and want firm support that doesn't broadcast every movement. It also suits you if one of you is tall, since the 200cm length gives 10cm more than a UK double, or if the dog has quietly become a permanent third sleeper.
Consider another size if...
Your bedroom is smaller than our suggested minimum of 2.7m x 2.9m 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 Miracoil Ortho UK king big enough for two people?
Yes, comfortably for most couples. At 150 x 200cm you get 75cm each for two people sharing, and Silentnight says the Miracoil springs support right to the edge, so neither of you loses usable width. Lightweight side sleepers should still note the firm feel before choosing it, whatever the size.
What room size do I need for the Miracoil Ortho in a UK king?
We suggest a room of at least 2.7m x 2.9m for a UK king, which leaves enough space to walk round the bed and open drawers. In a new build master bedroom, measure after allowing for wardrobes: rooms that look generous empty can feel tight once furniture is in.
Will the UK king reduce partner disturbance on this mattress?
It helps in two ways. The Miracoil spring system is designed to limit how much movement carries across the mattress, and the 75cm each for two people sharing means an early riser can get up with less chance of waking the other. No mattress removes disturbance entirely, but this combination reduces it.
Is the Miracoil Ortho UK king long enough for someone over six foot?
It is one of the better options. The UK king is 200cm long, or 6ft 6in, which is 10cm more than the UK single, UK small double and UK double. That extra length usually stops taller sleepers' feet hanging over the end. The UK super king is the same length, so sizing up only adds width.
Should I choose the UK king or the UK super king in this mattress?
The UK king is 30cm narrower than the UK super king, and both are the same 200cm length. If your room meets our suggested 3m x 2.9m minimum for the UK super king and you want maximum personal space, size up. If the room is tighter, the UK king is the more practical fit.