What size is a UK king-size mattress?

A UK king-size mattress is 5ft (150cm) wide by 6ft 6in (200cm) long. Each sleeper gets 75cm of width, 15cm more than a double. The length is the same as a super king. UK king is narrower than a US king (193cm) and not interchangeable, so do not use an imported mattress with a UK-bought frame.

How heavy is a king-size mattress?

Pocket sprung models weigh 30 to 50kg. Hybrid memory foam and latex run 40 to 60kg. Two-person lift is the standard for delivery and for turning. Roll-packed (bed-in-a-box) versions are easier to move into the house, but weigh the same once expanded.

How long does a king-size mattress last?

The Sleep Council recommends replacing a mattress every 7 to 8 years. Mid-market pocket sprung tends to hit that. Premium brands with hand-tufted construction (Hypnos, Vispring) often run 10 years or longer. Memory foam without a spring layer can sag earlier under heavier sleepers.

How thick should a king-size mattress be?

22 to 30cm covers most of the market. Below 22cm you are usually looking at a topper or a guest mattress. Pocket sprung and hybrid models need at least 25cm to fit the spring layer plus comfort fillings. Check headboard clearance before ordering anything over 28cm. The mattress can sit above the rail.

Will a king-size mattress fit through a standard UK door?

A standard internal door is 76cm wide. A 150cm-wide king-size mattress goes through on its side with room to spare. The pinch point is the stair turn, especially in older terraced houses with a quarter landing. Roll-packed bed-in-a-box mattresses solve this. They arrive in a 50cm by 50cm box.

MattressNextDay King-Size Mattresses (2026)

Best Mattress UK

By Jason · 18 May 2026
Garden Lighting

By Jason · 13 May 2026
How to Choose Curtains

By Jason · 9 May 2026
Garden Table and Chairs

By Jason · 8 May 2026
Sofa Bed Buying Guide

By Jason · 7 May 2026
The Coolflex mattress range, explained

By Jason · 5 May 2026

MattressNextDay King-Size Mattresses

353 MattressNextDay King-Size Mattresses from 14 UK Retailers in May ’26

Home Design & Furniture Styling Guides

Best Mattress UK

Garden Lighting

How to Choose Curtains

Garden Table and Chairs

Sofa Bed Buying Guide

The Coolflex mattress range, explained

Great prices, trusted stores

Product Categories

Shop With Confidence

Buying Ideas & Help