Awkward size mattresses

What is an odd size mattress?

An odd size mattress, sometimes called an awkward size mattress, is one made for a bed that isn't a standard UK single, small double, double, king or super king. The table compares these non-standard mattress sizes with a UK single (90 x 190 cm).

Shorty and small single mattresses mostly go on children's beds and in small spare rooms: shorty bunks, cabin beds, day beds and box rooms. Our shorty mattresses and small single mattresses pages cover each one in detail. The European single is one of a set of sizes that are all 200 cm long, explained in our guide to European size mattresses.

How do I measure my bed for a new mattress?

To measure a bed for a new mattress, take the old one off and measure the inside of the frame in centimetres: the width, the length and, for a raised bed or trundle, the deepest mattress it allows. That matters most when you need a mattress for an odd size bed, because bed names get used loosely and centimetres don't.

1. Measure the frame, not the mattress. An old mattress may have lost its shape, or may never have been the right size in the first place.
2. Take the width at the head, middle and foot. Older and home-made frames aren't always square, so go with the smallest figure.
3. Take the length down both sides. Again, use the shorter one.
4. Find the depth limit on raised beds and trundles. On a bunk, high sleeper, mid sleeper or cabin bed, measure from the slats up to the maximum mattress line marked on the frame. On a trundle, measure from the base of the drawer to the underside of the main bed.
5. Match the numbers. Compare your figures with the table above or with our mattress size guide.

What if my bed is between two standard sizes?

If your bed is between two standard sizes, it may be one of the rare ones: a frame about 107 cm wide inside, between a single and a small double, takes a large single (107 x 190 cm).

A large single (3ft6 x 6ft3) is 17 cm wider than a single and 13 cm narrower than a small double, so neither of those works in its frame: a single leaves a wide gap and a small double won't go in. At the narrow end, a frame about 60 cm wide takes a narrow 2ft (60 x 190 cm), made for spaces too tight for even a small single. That's the width each person gets when two share a small double, so a narrow 2ft suits a child or an occasional guest better than an adult every night.

Length can give a bed away too. A frame 200 cm long and 90, 120, 140 or 160 cm wide takes a European mattress, and the nearest UK mattress falls 10 cm short: in length for a single, small double or double, and in width for a king.

Why does an exact fit matter?

An exact fit matters because a mattress that's too small leaves a gap, one that's too big bows, and one that's too deep for a raised bed leaves less than the 16 cm of guard rail that BS EN 747 requires above it. On children's beds and raised beds, that makes fit a safety question.

• Too small: the mattress slides about, its edges have nothing to brace against, and bedding disappears down the side. On a child's bed, bunk or high sleeper, a gap between mattress and frame can trap a hand or foot.
• Too big: the mattress bows up in the middle or curls at the edges, so it never lies flat or supports you evenly.
• Too deep: on a bunk or high sleeper, a mattress that rises above the maximum mattress line leaves the guard rail too low to do its job. Our thin mattresses are all 16 cm deep or less, and our bunk bed mattresses page explains how the line works.

If your bed doesn't match any of the unusual mattress sizes here, send us its measurements through our contact page, including the depth limit if there is one, and we'll tell you what we can do. Our family runs this shop, and we'd sooner check the numbers with you than send out a mattress that nearly fits.

Written by the Mattress Town team. Last updated 9 October 2026.