Six sizes, two doorways too many parcels have got stuck in, and one European sizing trap that catches out anyone who’s bought a bed frame online. If you’re about to order a Silentnight mattress, the size question is where most of the expensive mistakes happen, not the firmness one.
This guide covers the standard UK sizes with their exact measurements, where UK and European “king” sizes genuinely differ, how much floor space each size realistically needs, which Silentnight ranges are confirmed to come in which sizes, and what to expect when a rolled mattress turns up at your door in a box smaller than you’d think possible.
TL;DR
- UK mattress sizes run Small Single (75x190cm) to Super King (180x200cm), with no standard UK “Queen” size.
- A UK King (150x200cm) is 10cm narrower than a Euro King (160x200cm), which trips up anyone using an IKEA frame.
- Silentnight doesn’t publish room-size guidance itself; third-party rules of thumb suggest roughly 76cm clearance around the bed.
- Boxed Silentnight mattresses generally expand within around 2 hours of unboxing, per the brand’s own Just Sleep page.
- The Healthy Growth kids range includes a 70x140cm toddler mattress despite one Silentnight category page listing it as 70x150cm.
What Are the Standard UK Mattress Sizes?
The UK uses six standard mattress sizes, from Small Single at 75 by 190cm up to Super King at 180 by 200cm. These measurements are consistent across Silentnight, Dreams, Which? and MattressNextDay’s own size guide, so you can shop between retailers without worrying the “double” you’re comparing is secretly a different size. Source: Silentnight
| Size | Centimetres | Imperial |
|---|---|---|
| Small Single | 75 x 190 | 2’6″ x 6’3″ |
| Single | 90 x 190 | 3’0″ x 6’3″ |
| Small Double | 120 x 190 | 4’0″ x 6’3″ |
| Double | 135 x 190 | 4’6″ x 6’3″ |
| King | 150 x 200 | 5’0″ x 6’6″ |
| Super King | 180 x 200 | 6’0″ x 6’6″ |
You’ll sometimes hear people ask for a “queen size” mattress. It isn’t a standard UK term on any retailer’s size chart we checked, though it gets used loosely by shoppers who’ve seen the word on American sites. If someone says “queen” in a UK context, they usually mean either a Double or a King, so it’s worth confirming exact centimetres before you order rather than trusting the label. Source: Which?
Not sure which size you currently have? Measure the mattress itself rather than guessing from the bed frame’s name, since older frames sometimes get relabelled by previous owners or estate agents. Lay a tape measure edge to edge across the width first, then the length, and round to the nearest 5cm. That figure will match one row of the table above almost every time, and it’s a more reliable starting point than trusting whatever the last person called it.
Is a UK King the Same Size as a European King?
No, and this is the size trap that causes the most returns. A UK King measures 150 by 200cm, but a Euro King measures 160 by 200cm, 10cm wider with the same length. Buy an IKEA bed frame and order a UK King mattress for it, and you’ll end up with a visible gap down one side. Source: Land of Beds
Our take: this catches out more people than you’d think, because “king size” reads as a universal term when it really isn’t. If your bed frame came from a European retailer or a flatpack furniture chain, measure the frame itself before ordering a UK-sized Silentnight mattress. It takes two minutes and it’s a lot less hassle than a return.
Which? and Dreams both confirm the same 150 by 200cm UK King figure independently, so this isn’t a one-source claim. Which? also lists a couple of less common European sizes worth knowing if you’re buying frame and mattress from different countries: Euro Single at 90 by 200cm and Euro Double at 140 by 200cm, both 10cm longer than their UK equivalents. There’s also an Emperor size at 200 by 200cm, though it’s rare enough in the UK market that most retailers, Silentnight included, don’t stock it. Source: Which?
How Much Room Do You Need for Each Mattress Size?
Silentnight’s own size guide doesn’t actually give room dimensions, so this is one area where you need a second source. Which? suggests roughly 76cm, about 2’6″, of clearance around the sides and foot of the bed as a general comfort minimum for walking round it and opening drawers. Source: Which?
| Size | Minimum suggested room |
|---|---|
| Single | 2.5m x 3m, with at least 60cm clear on one side |
| Super King | 4.5m x 4.5m, with at least 60cm clear on one side |
Room figures above are from The Sleep People’s buying guide, not Silentnight, since Silentnight doesn’t publish room dimensions. Treat them as a sensible rule of thumb rather than a strict rule. Source
Notice the gap in that table. We could only verify room-size figures for Single and Super King from a source we trust, not the four sizes in between. Rather than interpolate numbers nobody’s actually published, we’d rather tell you honestly: measure your own room with the exact mattress footprint plus that 76cm clearance figure, and you’ll get a more accurate answer than any generic chart could give you anyway.
Which Silentnight Ranges Come in Which Sizes?
Size availability varies by range, and it’s genuinely inconsistent across Silentnight’s catalogue, so check the specific product page rather than assuming. A handful of ranges are clearly documented; several others aren’t itemised in enough detail to state as fact. Four ranges have size data worth relying on here.
| Range | Confirmed sizes | Confidence |
|---|---|---|
| Mirapocket 1400 | Single, Double, King, Super King (no Small Single or Small Double) | Verified on this specific SKU’s product page |
| Miracoil range | Single through Super King, per listing titles | Moderately confirmed, not itemised per model |
| Eco Comfort 800 Pillowtop (Costco) | Listed as “5 Sizes” but not itemised on the product page | Low, don’t assume which five |
| Just Sleep (bed-in-a-box) | Seven mattress types, each in different sizes, per Silentnight’s own page | General claim confirmed, per-model sizes not itemised |
The Just Sleep line is Silentnight’s bed-in-a-box range, and the brand states it spans seven mattress types each available in different sizes, though it doesn’t break down exactly which sizes apply to which of the seven on a single page. Source: Silentnight Just Sleep If a specific size in a specific Just Sleep model matters to you, check that exact product listing rather than relying on the range page.
How Big Is a Silentnight Mattress When It Arrives Rolled and Boxed?
Smaller than the finished mattress by a wide margin, and it needs time to recover. Silentnight’s own Just Sleep page confirms these mattresses arrive rolled and boxed and typically expand to full size within roughly 2 hours of unboxing, which is the figure worth remembering over any specific box dimension. Source: Silentnight
We found a handful of specific box dimensions on retailer product pages, but Argos and Habitat’s own pages weren’t directly accessible when we checked, so these figures come from search-result snippets rather than a confirmed listing. Use them as a rough guide to how much hallway and stairwell space you’ll need, not as an exact spec.
Why does this matter for sizing specifically? Because a boxed mattress doesn’t scale down evenly. A Single rolls into a box roughly a third the weight of a King, but the length barely shrinks, since the mattress is rolled along its width rather than folded. A short hallway that would happily fit a Single’s box can still struggle with a King’s, even though the weight difference feels manageable on paper.
| Model | Approx. box size | Approx. weight |
|---|---|---|
| Just Sleep Dream Hybrid, King | around 44.5 x 44.5 x 165cm | around 45.4kg |
| Just Sleep Serene Hybrid, Double | around 44.5 x 44.5 x 145cm | around 41.7kg |
| Just Sleep Snug Memory Foam, Single | around 33 x 33 x 162cm | around 18kg |
Figures above are snippet-sourced estimates, not confirmed manufacturer specs. Confirm exact dimensions with the retailer before you order if stairwell or lift access is tight.
What the listings don’t tell you: a boxed super king is a two-person carry in most terraced and Victorian-conversion flats, not because of weight alone but because the box length, well over a metre and a half for a king, doesn’t bend round a tight stairwell turn the way you might hope. If you live somewhere with a narrow staircase, it’s worth asking the retailer about their unboxing or room-of-choice delivery service rather than assuming a courier will get it up on their own.
What Sizes Are Available for Kids’ Mattresses?
Silentnight’s Healthy Growth range covers toddler through to standard single sizes, with a mix of foam and pocket-sprung options depending on age and budget. The table below covers the models we could verify directly from product pages. Four models currently span that range, from a £109 toddler mattress up to full single-size options.
| Model | Size | Depth | Firmness | Price |
|---|---|---|---|---|
| Cosy Toddler | 70 x 140cm | 10cm | Firm | £109 |
| Starry Natural Pocket | 90 x 190cm (Single) | 27cm | Medium | Not itemised on fetched page |
| Kids 600 Pocket | 90 x 190 x 23.5cm (Single) | 23.5cm | Not confirmed | Not itemised (Argos, moderate confidence) |
| Kids Classic | 90 x 190 x 15cm (Single) | 15cm | Not confirmed | Not itemised (Argos, moderate confidence, bunk-suitable) |
The Cosy Toddler is built from EcoComfort fibres made from recycled bottles, is hypoallergenic and free of foam and flame-retardant chemicals, and comes with a 60-night trial and a 5-year warranty. Source: Silentnight The Starry Natural Pocket steps up to 600 Mirapocket springs and a British wool fill for a child moving into a standard single bed. Source: Silentnight
What the listings don’t tell you: Silentnight’s own site disagrees with itself on the toddler size. The Healthy Growth category page lists a 70x150cm cot bed, but the Cosy Toddler’s own product page says 70x140cm. The 140cm figure matches the universal UK cot-bed standard, so that’s almost certainly the correct one, and it’s what we’ve published above, but it’s worth measuring your own cot bed frame before ordering rather than trusting either page blindly.
For sizing across the wider Silentnight catalogue rather than just the kids’ range, our full Silentnight mattress review is the best starting point. If you’ve settled on the open-coil Miracoil construction, we’ve compared every current Miracoil model in detail. Short on time and want the shortlist instead of the full catalogue? Our ranked picks cover the best option by use case, including which one fits a hotel-style king setup like the Premier Inn Mattress 2.0. And once you know your size, compare retailers before you order, since delivery and returns terms differ more than people expect.
Before You Buy: Quick Answers
What size is a UK king mattress?
150 x 200cm (5’0″ x 6’6″). That’s 10cm narrower than a European King at 160 x 200cm, so check your bed frame’s origin before ordering if you’re not sure which spec it uses.
Is a UK double the same size as a queen?
There’s no standard UK “queen” size on any major retailer’s chart. A UK Double measures 135 x 190cm. If you’ve seen “queen” used, it’s most likely an American-sourced reference rather than a UK sizing standard, so confirm the exact centimetres before buying.
Will a rolled mattress fully expand once it’s unboxed?
Yes. Silentnight’s own guidance for its Just Sleep bed-in-a-box range states mattresses typically reach full size within roughly 2 hours of unboxing, though giving it a full 24 to 48 hours before final judgement is common sense for any compressed foam or hybrid product.
What size is the Silentnight Healthy Growth toddler mattress?
70 x 140cm for the Cosy Toddler model, matching the standard UK cot-bed size, despite one Silentnight category page separately listing 70 x 150cm. We’d trust the product page’s own spec over the category listing.
Do all Silentnight ranges come in every size?
No. Availability varies by range and sometimes by specific model within a range. The Mirapocket 1400, for example, skips Small Single and Small Double entirely. Always check the specific product page rather than assuming a range covers every size.
How much space do I need around a super king mattress?
As a rough guide, third-party buying guides suggest a room of roughly 4.5 x 4.5m with at least 60cm clear on one side, though Silentnight itself doesn’t publish room-size recommendations, so treat this as general advice rather than a brand specification.
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