Silentnight Rio Miracoil Cushion Top King Size Mattress
The Silentnight Rio Miracoil Cushion Top is a soft mattress with a cushioned sleep surface, listed as an eco-friendly design.
- Soft feel suits side sleepers
- Cushion top eases pressure points
- An eco-friendly choice
£387
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.
Silentnight Rio Miracoil Cushion Top Mattress
More available sizes
Last seen for £509 at Mattress Online on 25th June 2026
Mattress details
Mattress
Silentnight Rio Miracoil Cushion Top Mattress
Size
Firmness
Soft
Construction
Open Coil Spring
Eco-Friendly
Depth (cm)
Layers
3
Layer Details
Cushion top
A layer of soft white fibres sits at the surface to give a cushioned feel. It adds a little give under your shoulders and hips, so the mattress feels gentler than a bare spring top.
Dense polyester fibre layer
Below the cushion top is a dense layer of polyester fibres. It adds to the firm comfort and freshness, which means the surface doesn't feel too sink-in underneath the softer top.
Miracoil spring core
Miracoil continuous coil springs are divided into three separate zones of support. Each zone is there to support a different part of your body, which helps keep your hips and lower body held up while you sleep.
Layer details from mattressonline.co.uk and thesleepshop.co.uk product pages, October 2026.
Key benefits
- Proper space for two: At 150 x 200cm you get 75cm each for two people sharing, so you can settle into your own patch rather than negotiating the middle.
- Width offsets the soft feel: A soft mattress lets you sink in a little, and the UK king's extra width means you can do that without drifting into your partner's dip.
- Less disturbance on different schedules: If one of you gets up hours before the other, the wider surface puts more distance between you, so early alarms cause less of a stir.
- Length for taller sleepers: The UK king is 10cm longer than the UK double, which means anyone approaching six foot stops sleeping with their feet at the very edge.
- The largest size this mattress comes in: The Rio Miracoil Cushion Top tops out at the UK king, so this is as much room as the soft, cushioned feel gets.
This size suits you if...
You share the bed every night and a double has started to feel tight, you and your partner keep different hours and want enough width that one of you getting up does not wake the other, or one of you is tall enough that the extra length of the UK king is the real prize. It helps too if you both like a softer, cradling feel.
Consider another size if...
Your bedroom falls short of the 2.7m x 2.9m we suggest for a UK king. In that case we'd recommend the UK double instead, which needs at least 2.6m x 2.8m and keeps the same soft, cushioned feel.
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
How much space does each person get on the UK king Silentnight Rio?
The UK king measures 150 x 200cm, which gives 75cm each for two people sharing. On a soft mattress like the Rio Miracoil Cushion Top that width is genuinely useful, because a gentler surface lets each sleeper settle into their own area rather than rolling towards the middle.
Is the Silentnight Rio Miracoil Cushion Top in a UK king long enough for tall sleepers?
At 200cm, the UK king is 10cm longer than the UK double, and that length is often the real reason taller couples size up. If either of you is approaching six foot, the extra length stops feet hanging off the end, while the soft cushion top eases pressure on shoulders and hips.
What room size do I need for a king Silentnight Rio?
We suggest at least 2.7m x 2.9m for a UK king, with more feeling comfortable once wardrobes and bedside tables go in. New build master bedrooms can be smaller than they look on paper, so measure with furniture in mind. If space is tight, the UK double needs at least 2.6m x 2.8m.
Does a soft mattress like this cause roll-together in a king size?
Soft mattresses can exaggerate roll-together, particularly between partners of very different weights. The UK king helps rather than cures: 15cm wider than the UK double, it lets each of you sleep further from the centre, so the dip your partner creates is less likely to pull you in.
Can I get the Silentnight Rio Miracoil Cushion Top bigger than a UK king?
No, the UK king is the largest size this mattress is made in, alongside the UK single, small double and double. If you had a super king in mind, you would need a different mattress. For most couples the UK king's 150 x 200cm is a comfortable amount of space.