UK Mattress Sizes Explained 2026: Single, Double, King and Super King

Buying a new mattress in the UK should be straightforward — yet the sheer variety of sizes, combined with the lack of a single universal standard across countries, leaves many shoppers confused. What exactly is the difference between a Double and a King ? Is a Small Double wide enough for two people ? And if you are moving from continental Europe or the United States, will your existing bed frame even accept a British mattress ? This guide answers all of those questions with precise dimensions in centimetres and inches, practical advice on matching a size to your room and your sleeping habits, and a clear comparison with EU and US standards — so you can buy with confidence in 2026.

The five standard UK mattress sizes at a glance

The UK market recognises five mainstream sizes. The table below gives you the exact dimensions you will find on the vast majority of British mattress and bed-frame listings.

Note that both the King and Super King are 10 cm longer than Single, Small Double and Double models. This extra length — 200 cm versus 190 cm — makes a real difference for anyone taller than about 185 cm (6ft 1"), and is worth factoring in even if width is your primary concern.

Single (90 × 190 cm)

The Single is the entry-level UK mattress size and the default choice for children’s rooms, teenager bedrooms, bunk beds and guest rooms where space is tight. At 90 cm wide and 190 cm long, it offers enough room for one adult of average height to sleep comfortably, though taller sleepers — say, above 185 cm — may find the length slightly restrictive and should consider a King-size frame instead.

Single mattresses are also the most affordable option by a significant margin, and because they are so widely used, the choice of models, materials and firmness levels available in this size is enormous. From budget open-coil springs to premium natural latex, virtually every mattress technology is available in Single format.

One practical tip : two Single mattresses placed side by side make a reasonable 180 cm-wide sleeping surface, which is very close to a Super King in width. Some couples in rooms that cannot fit a standard king-size frame use this configuration, especially with zip-and-link bed frames designed for exactly that purpose.

Small Double (120 × 190 cm)

The Small Double — sometimes called a “Three-Quarter” bed — sits between a Single and a standard Double at 120 cm wide and 190 cm long. It is a popular compromise for adults living in city apartments, box rooms or studio flats where every centimetre counts, but who still want noticeably more sleeping space than a Single provides.

Can two people share a Small Double ? Technically yes, but at 120 cm wide, each person gets just 60 cm of personal space — roughly the width of a small armchair. For occasional guests sharing a spare room it is perfectly acceptable ; for a regular couple it tends to feel quite cramped over time. If you are buying a bed for two adults who will sleep together every night, the standard Double or — better yet — a King is a more comfortable long-term choice.

The Small Double is also a useful size for older teenagers who have outgrown a Single but whose bedroom cannot accommodate a full Double frame.

Double (135 × 190 cm)

The Double is the most widely sold mattress size in the UK and the standard starting point for couples. Measuring 135 cm wide by 190 cm long, it fits comfortably in a bedroom of around 10 m² once you allow for bedside tables and adequate clearance to walk around the frame.

A frequently quoted statistic worth keeping in mind : a standard Double gives each person sharing the bed roughly 67 cm of personal width — slightly less than the sleeping surface of a Single used solo. This is fine for couples who sleep close together or who do not move around much during the night. However, restless sleepers, people with different preferred sleeping positions, or those who simply value a feeling of space will often be happier upgrading to a King.

For solo adults, the Double is a generous and comfortable choice : you have ample room to sprawl, and the size is practical for most standard UK bedrooms. The Double is also compatible with the widest range of bed frames, headboards and bedding available in the UK market.

King (150 × 200 cm)

The King size — 150 cm wide and 200 cm long — is now the most popular bed size for couples in the UK, having overtaken the Double in recent years. The extra 15 cm in width over a Double may sound modest, but in practice it translates into meaningfully more personal space for each sleeper, reducing disturbance when one partner turns during the night.

The additional 10 cm in length (200 cm versus 190 cm) is equally important for taller people. At 200 cm, the King accommodates most adults well, with comfortable clearance for anyone up to around 190 cm (6ft 3") and acceptable room for those up to about 195 cm.

From a room-size perspective, a King-size bed frame typically requires a bedroom of at least 12–13 m² to allow comfortable circulation on both sides and at the foot of the bed. In a smaller room, the bed will fit physically but can feel overwhelming — always measure your room carefully before purchasing.

Super King (180 × 200 cm)

The Super King is the largest standard mattress size available in the UK, measuring 180 cm wide by 200 cm long. It is a genuinely luxurious sleeping surface — equivalent to placing two Single mattresses side by side — and is the go-to choice for couples who prioritise space above all else, as well as for families where young children or pets regularly join the bed.

At 180 cm wide, each person sharing a Super King has 90 cm of personal width : the same as a full Single mattress used solo. This makes a Super King genuinely comfortable even for restless sleepers or couples with very different firmness preferences (a zip-and-link Super King, made from two separate mattresses joined together, allows each half to have a different firmness).

The trade-off is room size : a Super King frame typically needs a bedroom of at least 14–16 m² to feel balanced, and bedding in this size — particularly fitted sheets — can be harder to find and more expensive. That said, for those with the space, a Super King represents a genuine upgrade in sleep quality and comfort.

How to choose the right size for your room and lifestyle

Room dimensions first. Before considering anything else, measure your bedroom accurately. Allow at least 60–70 cm of clearance on each side of the bed you intend to access regularly, and at least 90 cm at the foot if there is a wardrobe or door nearby. As a rough guide :

• 8–10 m² bedroom → Single or Small Double
• 10–12 m² bedroom → Double (comfortable), Small Double (generous)
• 12–14 m² bedroom → King (comfortable), Double (generous)
• 14 m²+ bedroom → Super King (comfortable), King (generous)

Solo or couple. A solo sleeper who values space will often be happiest on a Double. A couple sharing a bed every night should aim for at least a Double, and ideally a King if the room allows. The Super King is the premium choice for couples who are light sleepers, tall, or who simply want maximum comfort.

Height matters. If you or your partner are above 185 cm, strongly consider a King or Super King — both offer 200 cm in length versus just 190 cm on Single, Small Double and standard Double models.

Children and pets. If young children regularly come into your bed, or if a pet shares the sleeping surface, go one size up from what you would otherwise choose.

For a broader look at all the factors involved in selecting the right mattress — not just size but also firmness, materials and sleeping position — see our complete mattress buying guide .

UK vs EU vs US mattress sizes : key differences

One of the most common sources of confusion arises when people move between countries, inherit a bed frame from abroad, or order bedding internationally. UK sizes do not map perfectly onto either EU or US standards.

UK vs European sizes

European mattresses tend to follow a slightly different set of conventions. The most significant difference is length : where most UK Singles and Doubles measure 190 cm long, the equivalent European Single is typically 90 × 200 cm — the same width but 10 cm longer. European doubles are commonly 140 × 200 cm, which is 5 cm wider than a UK Double but 10 cm longer.

In practical terms, this means that a continental European fitted sheet will often be too long for a UK Single or Double mattress, and a UK mattress will not fill a continental European bed frame properly. Always check the exact dimensions rather than assuming the size name will translate between countries.

UK vs US sizes

The US uses entirely different size names, and the measurements do not align neatly :

The most important takeaway : a UK King (150 × 200 cm) is closer in size to a US Queen than to a US King. If you are importing a US bed frame or buying US-sized bedding, the size names will mislead you — always work from the centimetre dimensions.

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