King, super king and emperor sizes

The three biggest UK sizes are all 200 cm long. They differ only in width, by 30 cm and then 20 cm.

Checked against UK retailer and maker guides on 21 October 2026.

*Worked from MattressNextDay’s rule of at least 60 cm of walking space around the sides and foot of the bed, using the mattress size. Add the extra width of your frame. See bedroom size for each bed.

Super king: one mattress or two?

Which? notes a super king is the size of two standard singles side by side, and some are exactly that: two singles that zip together, so each person can choose their own firmness. A 180 cm zip-and-link pair is two 90 × 200 cm mattresses, which is 10 cm longer than a UK single.

Emperor

Which? and MattressNextDay list the emperor as 200 × 200 cm, a square. BedGuide warns the size varies by maker, so bedding is harder to find. Measure the mattress and buy bedding by centimetres, not name.

Why king duvets are wider than they are long

Which? lists a king duvet as 225 × 220 cm and a super king as 260 × 220 cm: wider than they are long. Some makers mark the shorter edge so you put the duvet into the cover the right way round.