Sofa Bed Sizes UK: Single, Small Double, Double and King Size Explained in cm

August 30, 2026

Sofa bed sizes are confusing because two numbers matter and retailers usually only shout about one. The width of the sofa tells you whether it fits the wall. The width of the bed tells you whether two adults can actually sleep on it. This guide sets out the UK sofa bed sizes from single to king, what each one means in centimetres, and the exact sofa and bed dimensions of every model made by Sofa Bed Expert (sofabedexpert.co.uk), so you can match the size to the room and the people sleeping in it.

Short version: single is 70 cm wide, small double 120 cm, double 140 cm and king size 150 cm. Every Sofa Bed Expert bed is 180 to 280 cm long, and most are 200 to 205 cm, longer than a standard UK bed.

UK sofa bed sizes explained

Sofa bed sizes borrow their names from UK mattress sizes. According to the standard UK bed sizes, a single mattress is 90 × 190 cm, a small double 120 × 190 cm, a double 135 × 190 cm and a king 150 × 200 cm. Sofa beds rarely match these exactly, which is why the name on its own is not enough. Our beds run wider than a standard double (140 cm rather than 135 cm) and longer than most standard beds (200 to 205 cm rather than 190 cm), with the single chair beds at 70 cm wide to keep the chair compact.

Single sofa beds (chair beds): 70 cm wide

A single sofa bed is a chair bed: an armchair 94 to 130 cm wide that opens into a 70 × 200 cm bed. The Oslo Chair Bed (94 cm, from £1,199), Millbrook Chair Bed (104 cm, £1,125) and Millbrook Storage Chair Bed (130 cm, £1,199) all share the same sleeping area. Read the full comparison in our chair bed guide.

Small double sofa beds: 120 cm wide

A small double is the size most two-seater sofa beds open to. It sleeps one adult in comfort or two who do not mind being close. In our range the Millbrook 2 Compact is only 154 cm wide as a sofa yet opens to 120 × 205 cm (£1,489). The Millbrook 2 Storage adds storage inside both arms at 180 cm wide, bed 120 × 200 cm (£1,550), and the Nap is another 154 cm two-seater with a 120 × 200 cm bed (£1,499). The Tampa Corner Storage is the corner option here: 227 × 160 cm closed, 120 × 205 cm bed (£2,299).

Double sofa beds: 140 cm wide

Our doubles are 140 cm wide, 5 cm wider than a standard UK double mattress, and sleep two adults properly. The Millbrook 3 Double is a 174 cm three-seater with a 140 × 200 cm bed (£1,550). The Millbrook 3 Double Storage is 200 cm wide with storage in both arms and a 140 × 205 cm bed (£1,699), and there is an in-stock Millbrook 3 Storage with matching storage footstool in Marble Velvet Lunar Rock at £1,599.

King size sofa beds: 150 cm wide

King size is the sofa bed size to choose if it will be slept on every night, because 150 cm gives two adults the same width as a real king bed. What surprises most people is how little sofa you need for it. The Oslo King Size is just 170 cm wide and opens to 150 × 205 cm (from £1,699). The Millbrook King Size is 184 cm wide, bed 150 × 205 cm (£1,650), and the Millbrook King Size Storage adds arm storage at 210 cm wide (£1,799).

For a corner layout, the Mocca King Size Corner is 235 × 150 cm closed with a 150 × 200 cm bed and two storage compartments (£1,899), while the slimmer Mocca Grande, Mocca Flow and Mocca Rosso are 235 cm wide but only 108 cm deep, all opening to 150 × 200 cm (£1,789 to £1,849). The compact Mocca Mini corner is 200 × 150 cm closed and opens to 150 × 180 cm (£1,849): full king width but a shorter bed, so check it against your height.

The biggest: U-shaped, 150 × 280 cm

The Mocca U-Shaped Sofa Bed is 315 cm wide and 150 cm deep as a sofa, with three storage compartments, and it opens into a 150 × 280 cm sleeping area, long enough for two adults with a child at the end, or for tall sleepers who never have enough length. It is rated to 500 kg and costs £2,389.

Every Sofa Bed Expert size in one table

All models are 90 to 96 cm high, use a pocket sprung seat and mattress on a plywood frame, and include free delivery and installation across England, Wales and Scotland.

Which size should you choose?

• One person, occasionally: a single chair bed or the Millbrook 2 Compact small double.
• Two guests a few times a year: a 140 cm double such as the Millbrook 3.
• Sleeping on it every night, or a couple: king size. The Oslo King fits a 170 cm wall; the Millbrook King is the best-value option at £1,650.
• Family room, films and sleepovers: a Mocca corner, or the U-shaped for the largest bed.
• Tall sleepers: pick a 205 cm bed (Millbrook, Oslo, Tampa) or the 280 cm U-shaped, and avoid the 180 cm Mocca Mini.

"The Mocca King Size Corner Sofa Bed is incredibly comfy both as an everyday sofa and as a proper bed for nightly sleep."
Alex Bertzeletos, verified customer review

Frequently asked questions

What are the standard sofa bed sizes in the UK?

Sofa beds are sold as single, small double, double and king size, borrowing names from UK mattress sizes. At Sofa Bed Expert a single bed is 70 cm wide, a small double 120 cm, a double 140 cm and a king 150 cm, with bed lengths of 200 to 205 cm on most models.

How wide is a king size sofa bed?

A king size sofa bed has a 150 cm wide mattress. As a sofa, Sofa Bed Expert king size models range from 170 cm wide (Oslo King Size) to 235 cm wide (Mocca corner models), so the sofa width and the bed width are different measurements.

What is the smallest sofa bed that sleeps two adults?

The Millbrook 2 Compact is 154 cm wide as a sofa and opens to a 120 × 205 cm small double, which suits two adults at a squeeze. For two adults in comfort, the 170 cm wide Oslo King Size opens to a full 150 × 205 cm king bed.

How long is a sofa bed mattress?

Most Sofa Bed Expert sofa beds have a 200 or 205 cm long mattress, which is longer than a standard 190 cm UK bed. The Mocca Mini is shorter at 180 cm, and the Mocca U-Shaped is the longest at 280 cm.

Is a double sofa bed the same size as a double bed?

Almost. A standard UK double mattress is 135 × 190 cm. Sofa Bed Expert double sofa beds are 140 cm wide and 200 to 205 cm long, so they are slightly wider and noticeably longer than a standard double bed.

What size sofa bed do I need for everyday use?

For every-night use by a couple, choose a king size (150 cm wide) sofa bed with a pocket sprung mattress. Sofa Bed Expert king size models start at 170 cm wide as a sofa and £1,650 in price.

How much floor space does a sofa bed need when open?

Add the bed length to the space in front of the sofa. A Millbrook King Size, for example, is 96 cm deep closed and needs about 205 cm of depth open, because the mattress unfolds forward. Corner models like the Mocca open into the room without needing a gap behind them.

What is the biggest sofa bed available?

The Mocca U-Shaped Sofa Bed from Sofa Bed Expert is 315 cm wide and opens to a 150 × 280 cm sleeping area with three storage compartments. It is rated to a 500 kg weight capacity and costs £2,389.

The bottom line

Measure the wall, then measure the people. A 70 cm single, 120 cm small double, 140 cm double or 150 cm king each has a place, and with the sofa widths above you can see exactly which combination fits your room. If you are going to sleep on it regularly, go king: the extra 10 cm over a double is the difference between a sofa bed and a bed.

Related reading: King size sofa bed UK · Chair beds guide · Corner sofa beds

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