UK bed and mattress sizes

Which size suits which household

Work from who is going to be in the bed, not from the room, and then check the room will take the answer.

Behind that table sits one piece of arithmetic. Halve the width and you get what each person in a shared bed actually has: 60 centimetres in a small double, 67.5 in a double, 75 in a king and 90 in a super king. A cot is 60 across and a single is 90, which is why a double is tighter than its reputation and a super king feels like two separate beds.

Two things follow from that, and neither appears on a specification sheet. The narrower the shared bed, the more the construction matters, because below king width you are close enough to feel the other person turn over, and springs that are wired together move as one surface. And where two people want different firmness, width is what makes it possible at all.

Height decides before width does

Settle the length before any of the width arithmetic, because it rules sizes out rather than making them less comfortable. The smaller four sizes are 190cm long and king and super king are 200.

Give the tallest sleeper 10 to 15 centimetres of clearance and the 190 sizes stop working at about 5'11", the 200 sizes at about 6'3". Anyone taller is choosing between a made-to-measure length and sleeping with their feet over the end.

Which makes a tall couple in a small room a harder problem than a short couple in a large one. The extra length is only sold at king width and above, so the bed grows in the direction they did not need and the floor plan has to absorb it. A footboard removes the fallback entirely, since feet cannot overhang a sleigh or a panelled frame at all.

The room, and the space around the bed

A bed does not end at the edge of the mattress. It needs a strip down each side wide enough to walk along and to stand in while you make it, and that strip wants 60 to 75 centimetres. Under 60 you can get past it but you cannot work beside it, and tucking in the far corner becomes a daily annoyance nobody anticipates in a showroom.

Worked through, that puts a double in a room about 2.6 metres wide, a king in about 2.7 and a super king in about 3.1, measured wall to wall across the bed. Those figures assume clear floor on both sides and nothing opening into it, so add to them for wardrobe doors that need their own swing, for a radiator that should not be boxed in behind a headboard, and for a bedroom door that opens inward on the side the bed sits.

Length deserves the same treatment and rarely gets it. A 200 centimetre bed in a three metre room leaves a metre at the foot, which sounds generous until a chest of drawers is standing in it and somebody has to open a drawer.

Where the sums do not work, the honest conclusion is to go down a size. A king you can walk round is a better bed than a super king you have to climb over, and the extra 30 centimetres buys 15 each, which is less than the step from a double to a king.

The frame adds to the footprint

Every size on this page is a mattress size. The bed that carries it is bigger, and by how much depends entirely on the type, which is the step most room plans leave out.

A divan is the tightest fit, because the base is built to the mattress and only a headboard projects beyond it. A bedstead adds the thickness of its side rails and the span of its legs, and a wide wooden frame can add ten centimetres or more across. A sleigh or panelled frame adds a footboard, which takes length at the foot and removes any possibility of overhang. An upholstered frame adds padding on every side it has.

Two types need clearance a floor plan will not show. An ottoman lifts the whole mattress on gas struts, so it wants height above the bed and standing room at the end you lift from. A bed with drawers needs those drawers to come fully out, which is a strip of clear floor as deep as the drawer, at one side or at the foot.

So plan the room to the frame's external dimensions rather than to the size name. Where a listing gives only the mattress size it is built for, that is a question to ask before ordering.

Check the centimetres before the name

A size name is only a reliable instruction inside one country. British, continental and American ranges all use single, double and king for beds of different widths, and all three turn up in UK listings, imported frames and flat-pack ranges especially.

The habit that prevents the mistake is simple. Find the two figures in centimetres on the listing, write them down, and buy the frame, the mattress and the bedding to those figures rather than to the word. Every UK size in centimetres, against its European and American near-equivalents, has the comparison in full.

Zip and link, where access or firmness is the problem

A zip and link bed is two mattresses that join down the middle on one base, and it is the standard answer to two problems that have nothing to do with comfort.

Access. Each half is a single, so it goes up a staircase and round a landing that a king or super king will not. Where the route into the room is the binding constraint, this is the only way to get a large sprung mattress onto the bed at all.

Two people who want different firmness. Each side is specified on its own, which is more complete than any dual firmness mattress, because there is no transition zone to lie on, only a join.

It keeps the bed maintainable too, since one person can turn a single where a super king needs two. The sizes work out exactly and the combinations are listed with the rest of the dimensions. The thing to know before committing is that you can feel the join if you sleep down the middle.

The measurement the size name leaves out

A size name fixes the length and the width and says nothing at all about the depth, which is not standardised and which decides whether your sheets and your frame will take the mattress.

So write the depth down beside the other two figures when you measure, because every later purchase for that bed depends on it. The depths modern mattresses run to, and what a standard sheet is cut for, are on the sizes in centimetres page.

Measure the base, not the old mattress

The mattress already on the bed is the worst available guide to the size you need. It has compressed, it may have distorted at the corners, and on a bed more than a few years old it can read two or three centimetres under its own nominal size.

Measure the frame instead, from the inside. Take the length and the width at the longest and widest internal points, because rails are not always parallel and in an older frame they rarely are. Write both figures down in centimetres rather than trusting them to memory.

Then take two more. The depth the frame will accept, which is a stated maximum on bunks, trundles, day beds and anything with a footboard. And the slat spacing, which wants to stay inside about 7.5 centimetres if the mattress is not to settle into the gaps and lose its guarantee doing it.

Expect a centimetre or two of variation even within a standard size. Makers are not held to the nominal figure, and the tolerance matters most on frames where the mattress has to drop between a headboard and a footboard rather than sit proud on a platform.

Last, measure the route and not only the room: the doorway at each end of it, the staircase at its narrowest, the turn onto the landing, and any low ceiling over the stairs. A sprung king or super king does not bend, so a route that is a few centimetres short is a delivery that leaves again on the van.

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