UK Mattress Sizes Explained: Single To Emperor

Standard UK Mattress Sizes

The UK uses its own sizing system, separate from European and US standards. Sizes are traditionally described in feet and inches, though manufacturers increasingly list centimetres alongside.

Here are the standard sizes you will find in most UK shops:

• Small single: 75 x 190 cm (2'6" x 6'3")
• Single: 90 x 190 cm (3'0" x 6'3")
• Small double: 120 x 190 cm (4'0" x 6'3")
• Double: 135 x 190 cm (4'6" x 6'3")
• King: 150 x 200 cm (5'0" x 6'6")
• Super king: 180 x 200 cm (6'0" x 6'6")
• Emperor: 200 x 200 cm (6'6" x 6'6")

Notice that king and super king mattresses are 10 cm longer than the smaller sizes. If you or your partner are over 183 cm (6'0") tall, a king or larger is worth considering for the extra legroom alone.

Room Size Requirements

A mattress needs clear space around it for access, airflow, and furniture. As a working minimum, allow 60 cm on at least two sides of the bed and 90 cm at the foot.

Based on those clearances, each size fits comfortably in:

• Single: rooms from 2.1 x 3.0 m (7 x 10 ft)
• Double: rooms from 3.0 x 3.0 m (10 x 10 ft)
• King: rooms from 3.0 x 3.7 m (10 x 12 ft)
• Super king: rooms from 3.7 x 3.7 m (12 x 12 ft)
• Emperor: rooms from 3.7 x 4.3 m (12 x 14 ft)

Measure the room before ordering. A super king mattress in a 3.0 x 3.0 m bedroom leaves almost no floor space for wardrobes or side tables.

Children's And Cot Sizes

Children's mattresses follow separate standards:

• Cot mattress: 60 x 120 cm
• Cot bed mattress: 70 x 140 cm
• Junior or toddler bed: 70 x 140 cm (same as cot bed, fits standard toddler frames)
• Small single: 75 x 190 cm (commonly used from age six or seven onwards)

Safety standards require cot and cot bed mattresses to fit snugly within the frame. A gap of more than 3 cm between the mattress edge and the frame is a suffocation risk. Always measure the internal frame dimensions before buying a replacement.

Choosing The Right Size

For a single adult, a double (135 cm wide) is the practical minimum for a comfortable night. A single mattress works in spare rooms and children's bedrooms, but most adults find 90 cm too narrow for regular use.

For couples, a king (150 cm) gives each person 75 cm of width, the equivalent of a single bed each. If either partner moves around or is broad-shouldered, a super king (180 cm) makes a noticeable difference to sleep quality.

Height matters as much as width. Standard UK singles and doubles are 190 cm long. Anyone over 183 cm should choose a king or super king for the extra 10 cm in length.

If you are also shopping for a bed frame, our guide to ottoman and divan storage beds covers which frame types work best for each size. And if you are unsure which mattress type to go for, the memory foam vs pocket sprung comparison breaks down the main options.

Buying Tips

• Always check whether the retailer lists sizes in UK or EU dimensions. Some online shops sell EU sizes, which differ slightly. An EU double is 140 x 200 cm, for example, 5 cm wider and 10 cm longer than a UK double.
• Bed frames and mattresses should come from the same sizing system. A UK king mattress on an EU king frame will leave gaps at the sides.
• If you are replacing a mattress on an existing frame, measure the frame's internal dimensions rather than relying on the size label. Older frames sometimes use non-standard measurements.
• Sheets, protectors, and toppers are all size-specific. If you upgrade from a double to a king, you will need new bedding to match.

For live prices on specific sizes across UK mattress retailers, check our mattress listings page.