Why choose a Silentnight king size mattress?
A Silentnight king size mattress gives couples more room to sleep comfortably without requiring as much floor space as a super king. You can choose from different firmness levels, fillings and support systems, including responsive Mirapocket® springs and even Miracoil® support.
Selected options also include memory foam, breathable Eco Comfort Fibres™ and hypoallergenic finishes. With a wide choice of comfort levels and prices available, it’s easy to find a Silentnight king size mattress that suits your sleeping style, bedroom and budget.
How to choose the right Silentnight king size mattress
A king gives each sleeper 75cm of width. Begin with your usual sleeping positions and preferred firmness, then compare partner movement, edge support and temperature control.
Mirapocket® is a great option if either of you changes positions frequently. Its springs move independently, which can reduce motion travelling across the mattress. Miracoil® creates a firmer, steadier response across the full width and supports you towards the edges.
Finding the perfect firmness for you and your partner
Firmness describes the amount of surface give rather than the overall quality of support. Body weight, comfort layers and the bed base can all change how a mattress feels, so compare the comfort rating with the complete specification.
Firmness | Who it may suit |
Soft | Side sleepers and lighter sleepers who want deeper cushioning at the shoulder and hip |
Medium | Side and combination sleepers, plus couples seeking a versatile shared feel |
Medium firm | Back, front and combination sleepers who want cushioning over a steadier core |
Firm | Many front and back sleepers, or anyone who prefers less sink at the surface |
Side sleepers often prefer soft or medium cushioning around the shoulder and hip. Many back and side sleepers choose medium firm or firm support to limit sinking around the middle.
If your preferences differ, begin with medium or medium firm and prioritise Mirapocket® springs. Their independent response lets each side adapt more locally.
Why shop at MattressNextDay?
Next day delivery - Next day delivery available for eligible in-stock mattresses across mainland UK.
Lowest price promise - Compare trusted king size mattresses backed by price reassurance.
Old mattress removal - We’ll remove your existing mattress when your new mattress arrives.
Excellent reviews - Read and compare verified customer reviews before you buy.
Award-winning retailer - Buy from a three-time NBF Online Bed Retailer of the Year.
British-designed quality - Explore British-designed mattresses made with thoughtfully selected materials.
Need help choosing your next mattress?
Answer a few questions in MattressFinder™ about who will use the mattress, how you sleep, your preferred firmness and budget. Find your perfect mattress.
Buying guidance for Silentnight king size mattresses
Choosing your Silentnight king size mattress is easier once you know which materials, comfort features and dimensions will work for you. Below, you can explore the benefits of Eco Comfort Fibres™, compare king and super king sizes, and check the practical details that will help you order with confidence.
Eco Comfort: Sustainable sleep with recycled materials
Choose Eco Comfort Fibres™ if you want breathable cushioning with a fresher, cooler feel. The open fibres allow air to circulate through the comfort layer and have been scientifically proven to help keep you cooler while you sleep.
Sourced sustainably and made using 100% recyclable fibres, they offer a more environmentally considered way to add comfort without stretching your budget. Compare the available firmness levels and spring systems to find the right Eco Comfort mattress for you.
King size vs super king: Which dimensions suit your bedroom?
A standard UK king measures 150cm x 200cm, or 5ft x 6ft 6in. It is 15cm wider and 10cm longer than a double. A super king is 180cm x 200cm, giving each sleeper around 90cm of width.
What to measure | What to check |
Bed frame | Measure inside the frame and confirm it is a standard UK king at 150cm x 200cm. Continental and European frames can use different dimensions. |
Bedroom space | Mark out the full 150cm x 200cm footprint, then check that doors, wardrobes and drawers can open and you can walk comfortably around the bed. |
Delivery route | Measure doorways, stairs, turns and landings. This is particularly useful for deep pillow-top or box-top mattresses delivered flat. |
Slatted base | Check that the slats are secure, evenly spaced and within Silentnight’s stated spacing requirements. A king frame should also have suitable central support. |
Divan base | Confirm both halves sit level, join securely and match the mattress dimensions. A sprung divan can make the mattress feel softer than a firm platform top. |
Bedding depth | Check the mattress depth before ordering fitted sheets and a mattress protector. Deep pillow-top and box-top models may need extra-deep bedding. |
Choose a king for more personal space than a double. Consider super king if both sleepers spread out and the room and delivery route can accommodate the extra 30cm.
Delivery, recycling, and guarantees
Free next-day delivery to most locations - Choose an in-stock Silentnight king size mattress and order before the stated cut-off. Selected products qualify for free next day delivery to most locations.
Free weekend delivery - Select a weekend date where available, giving you time to clear the room, dismantle the old bed if needed and arrange help at home.
Choose a delivery date - Check the dates at checkout and select one that fits your move, work schedule or bedroom update.
Learn more about our delivery and returns policies.
We make old mattress disposal easy for you
Just £39 to responsibly dispose of your old mattress - Add removal at checkout and we’ll collect your old mattress when the new one arrives.
100% of your mattress is reused and recycled - Your old mattress is broken down so its materials can be reused and recycled, keeping the whole mattress out of landfill.
A greener way to get rid of your old mattress - Avoid the hassle of arranging mattress disposal yourself and choose a recycling service designed to work around your needs.
Find a great value Silentnight king size mattress
Check the latest offers on Silentnight king size mattresses, including pocket-sprung, firmer and cooling models. Shop mattress sale.
Ask the expert about Silentnight king size mattresses
Still weighing up mattress dimensions, firmness, and spring systems?
Martin Seeley, Product Expert at MattressNextDay, answers questions about Silentnight king size mattresses.
How much do Silentnight king size mattresses cost?
Silentnight king size mattresses at MattressNextDay vary in price, meaning there’s something for everyone.
At the lower end, you can find Miracoil®, memory foam and lower spring-count Mirapocket® models. Mid-range choices add deeper fillings and reinforced edges. Higher-priced options can include advanced cooling fabrics, latex and box-top construction.
Our Lowest Price Promise protects the value of your final choice. We monitor our main listed competitors and refresh our prices every 24 hours. If a listed competitor sells an identical mattress for less, we’ll match that price, and you’ll still receive our fast delivery and customer care at no extra cost.
What is the difference between Mirapocket® and Miracoil®?
On a wider mattress, the spring system affects partner movement and support near the edges. Silentnight’s zoned constructions vary the response across the body, providing steadier support around heavier areas and pressure relief where needed.
| Mirapocket® | Miracoil® |
Feel | More adaptive, with localised give beneath each sleeper | Firmer and more even across the sleeping surface |
Support | Individually wrapped springs respond separately to weight and position changes | A continuous zoned spring unit provides targeted, edge-to-edge support |
Breathability | Air can pass through the sprung core, while the fillings and cover determine how cool it feels | Its open spring construction supports airflow through the mattress |
Movement | Independent springs help limit motion transfer and reduce roll-together | Connected springs create a more unified response when either sleeper moves |
Best suited to | Couples with different weights or sleep positions, and light sleepers who notice partner movement | Couples or solo sleepers who prefer a stable, firmer feel and want support towards the edges |
Is Mirapocket® or Miracoil® better for couples?
Mirapocket® is often the stronger choice when partner movement is the main concern because each spring responds independently. Miracoil® may suit couples who both prefer firmer, edge-to-edge support and a more uniform surface.
Compare the firmness and comfort layers, as well as the spring type, since these features also affect pressure relief and the overall feel.
What are the dimensions of a Silentnight king size mattress?
A Silentnight king size mattress measures 150cm wide by 200cm long, or 5ft by 6ft 6in. Check the internal dimensions of your bed frame before ordering, especially if it is European or imported, as a non-UK king can use different measurements.
Do Silentnight king size mattresses arrive rolled or flat?
It depends on the model. Selected mattresses are vacuum packed and rolled, making them easier to move through tight doorways, while deeper sprung and pillow-top models may arrive flat. Check the product page, measure your route and allow a rolled mattress to expand for the stated time before use.
Which Silentnight king size mattress should I choose for back pain?
No mattress can treat or cure back pain, although a supportive surface may feel more comfortable.
Many sleepers compare medium firm or firm models with zoned support. Miracoil Ortho has a steady, firmer feel, while Mirapocket® models respond more locally and can include cushioning memory foam or UltraGel® layers.
How long is the guarantee on a Silentnight king size mattress?
Silentnight king size mattresses include at least a five-year manufacturer’s guarantee against qualifying manufacturing issues.
Cover and terms can differ, so check the product page, keep your proof of purchase and follow the care instructions.
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