King Size Sofa Beds: Dimensions, Fit, and the Best Option for Couples

A true king-size sofa bed is rarer than the label suggests — the term is often stretched, and many products labelled "king" don't open to a full king surface. A genuine king-size sofa bed opens to a 150 x 200 cm sleep surface, matching a standard UK king mattress and giving couples noticeably more room than a double. Before you buy, it's worth knowing what "king" actually means in the UK, why relatively few sofa beds reach that size, and which sofa bed gives couples a proper night's sleep without a super king footprint.

Key takeaways

• A true UK king size sofa bed opens to a 150 x 200 cm sleep surface.

• Koala's UK sofa bed — the Koala Sofa Bed [4th Gen] — comes in three sizes: Single, Double and 3-Seater (King).

• The 3-Seater (King) opens to a 155 x 209 cm surface — a genuine UK king, built for two.

• Prices start from £1,495 for the King; it ships flat-packed with free UK delivery and tool-free assembly.

• Every size has a Kloudcell™ mattress topper, machine-washable covers, a 120-day trial and a 5-year warranty.

What counts as a true king size sofa bed?

A true king size sofa bed unfolds to a 150 x 200 cm sleeping surface — the dimensions of a standard UK king mattress. Anything smaller is a king in name only.

That distinction matters, because the label gets stretched. If you're searching for the best king size sofa bed, start with what the label actually means: some listings quote the sofa's width rather than the mattress as the size claim, while others fold out to a surface that's narrower or shorter than a real king. King sofa bed dimensions worth trusting always state the open sleep surface separately from the sofa footprint. Before you buy any sofa bed, check two numbers: the open sleep surface and the closed sofa width.

For reference, here are the standard UK bed sizes:

Why king size sofa beds are rare

Genuine king size sofa beds are rare because a sofa big enough to house one usually won't fit through a standard UK doorway in one piece — and super king fold-outs are harder still to find.

A sofa that houses a king usually measures 175 cm or more wide when closed and needs around 220 cm of clear floor depth when open, plus walkway space around it. Delivery is the other problem. UK internal doors are commonly 762 mm wide, ranging from roughly 686 mm to 838 mm — and the clear opening is a little narrower than the door itself. A fully assembled sofa that houses a king often won't clear that, let alone a hallway turn or a stairwell. That's one reason many sofa beds top out at a double — it tends to be the largest size that still fits comfortably through the doors and halls of a typical UK home. Flat-packed designs that assemble inside the room sidestep the doorway problem entirely — which is how a genuine king becomes practical.

The Koala king size sofa bed

Koala makes one sofa bed — the Koala Sofa Bed [4th Gen] — in three sizes, and the largest, the 3-Seater (King), opens to a genuine king-size sleep surface of 155 x 209 cm.

That's a touch larger than a standard UK king, built for two, and it arrives flat-packed so the doorway problem never applies. Prices below are regular, at the time of writing; Koala runs frequent promotions, so check the live product page for current offers.

Best for couples: 3-Seater (King)

The 3-Seater (King) is the pick if you want true two-person, king-size sleep. It's 178 cm wide as a sofa and opens to a bed slightly longer and wider than a standard UK king.

Its sit-to-sleep design flips from sofa to bed in seconds — no bars, no springs, no frame to wrestle. An integrated Kloudcell™ topper adds the open-cell foam comfort layer from Koala's award-winning mattress range, and the deep 63 cm seats (a plush 60 cm seat cushion) make it a proper everyday sofa, not just a guest bed. And because it arrives flat-packed, doorways aren't a problem. Rated 4.9 stars across 1,642 reviews at the time of writing. Browse the full range in the 3-Seater sofa beds collection.

Smaller in the room: 2.5-Seater (Double) and 1.5-Seater (Single)

If a king is more than your room needs, the same sofa bed comes smaller. The 2.5-Seater (Double, 162.5 cm wide) folds out to a double and suits most living rooms; the 1.5-Seater (Single, 121.9 cm wide) opens to a single and is built for studios, small flats, home offices and spare rooms. Both are built exactly like the King — just scaled to the room. Compare options in the double sofa beds collection.

Complete your setup: the Koala Sofa Bed Ottoman

The Koala Sofa Bed Ottoman (from £320, an optional add-on) gives you hidden storage for guest bedding and a flippable hard top that doubles as a side table — the practical finishing touch for a king sofa bed used by overnight guests.

Lift the lid, and there's room for bedding and spare covers, so your living room stays a living room between visits. Flip the top over, and it becomes a stable side table for a lamp or a morning coffee. It comes in the same Koala-exclusive, washable fabrics as the sofa bed, sits on an FSC®-certified timber frame and assembles tool-free. Pair it with the sofa bed if you host regularly — see the full Koala Sofa Bed Ottoman, or browse sofa beds for overnight guests to plan a guest-ready setup.

Fabrics, comfort and everyday use

The Koala Sofa Bed comes in eight Koala-exclusive fabrics that are removable, machine-washable and (on most finishes) water-resistant — so a king sofa bed works as your daily sofa as well as a guest bed.

Because a king-size sofa bed usually earns its space by working every day, the fabric matters as much as the mattress. Koala's finishes span Classic, Cord and Luxe ranges in eight colours, are PFAS-tested, and contain recycled content. Covers unzip and cold-machine-wash at 30°C, then line-dry — handy if it doubles as a family or film-night sofa.

How to choose a sofa bed for two

Check five things in order — mechanism, sleep-surface quality, doorway clearance, open-depth room fit, and washable covers.

1. Mechanism type. Fold-out metal frames put a thin mattress over bars — the classic sofa bed complaint. Mechanism-free, sit-to-sleep designs like the Koala Sofa Bed [4th Gen] put the sleep surface on solid support instead.

2. Sleep surface quality. Look for a named comfort layer and a full-size mattress, not vague "high-density foam" claims. The Koala Sofa Bed uses a full-size mattress with an integrated Kloudcell™ comfort layer.

3. Doorway clearance. Measure every door, hallway turn and stairwell on the delivery path — or skip the problem with a flat-packed design that assembles tool-free in the room.

4. Open-depth room fit. Measure from the wall and leave about a metre of walkway beyond the open bed. The 3-Seater (King) needs roughly 222 cm of clear depth when open.

5. Covers and cleaning. If the sofa doubles as your everyday sofa, machine-washable removable covers matter. Every size of the Koala Sofa Bed has them.

King size vs double sofa bed: which should you buy?

Buy a king if couples will sleep on it regularly and you have the space; choose a double for smaller rooms or occasional guests.

A king's advantage is 15 cm of extra width plus 10 cm of extra length — meaningful for two sleepers, less so for one. A double's advantage is a smaller closed footprint and easier delivery. Super king sofa beds (180 x 200 cm) are worth a mention only to rule out: they're hard to find as a fold-out, and rarely worth hunting down when a genuine king already sleeps two comfortably.

Not sure a king will fit? The Koala Sofa Bed [4th Gen] comes in King, Double and Single, so you can match the size to your room — all with a Kloudcell™-topped sleep surface and flat-packed, tool-free assembly. Try it at home with Koala's 120-day free trial.

Delivery, assembly, trial and warranty

The Koala Sofa Bed ships free across mainland UK (some remote-area exclusions), usually within 7 days, flat-packed for tool-free assembly, with a 120-day home trial and a 5-year warranty.

Delivery is free to England, Scotland and Wales, with exclusions for Northern Ireland, the Scottish Highlands & Grampian, the Isle of Man, the Channel Islands, the Isles of Scilly, Scottish offshore islands and the Isle of Wight. It arrives in five flat boxes and assembles without tools — parts slot, screw and zip together with alignment guides and coloured tabs, so there are no Allen keys involved. If it isn't right, the 120-day trial covers a full refund including delivery, with free collection, and Koala is a certified B Corp that re-homes returns sustainably.

Frequently Asked Questions

What size is a king sofa bed?

In the UK, a true king sofa bed opens to a 150 x 200 cm sleeping surface — the same as a standard UK king mattress. The sofa itself is usually 175 cm wide or more, so check both the open sleep surface and the closed footprint. The Koala Sofa Bed [4th Gen] in 3-Seater (King) opens to 155 x 209 cm.

Will a king sofa bed fit through a standard doorway?

Many won't in one piece — UK internal doors are commonly 762 mm wide, and a fully assembled king sofa's depth often exceeds the clear opening. Measure doorways, hallways and stairwells first, or choose a flat-packed design like the Koala Sofa Bed [4th Gen], which arrives in boxes and assembles tool-free in the room.

Is a double sofa bed big enough for two adults?

Yes — a standard double (135 x 190 cm) sleeps two adults, and its smaller closed footprint suits compact rooms. If you want more room, the Koala Sofa Bed [4th Gen] also comes in a 3-Seater (King) that opens to a king-size surface designed for two.

How much does a king size sofa bed cost?

UK king-size sofa beds vary widely by build quality. The Koala Sofa Bed [4th Gen] in 3-Seater (King) starts from £1,495 at the time of writing, with the Double from £1,395 and the Single from £1,250. Check the live page for current offers.

Are sofa beds comfortable enough for everyday sleeping?

A good one is. The difference is the sleep surface: the Koala Sofa Bed uses a full-size mattress with an integrated Kloudcell™ topper on solid support, rather than a thin pad over a metal bar frame, so it suits regular use as well as guest nights.