A king size mattress is 150 × 200cm — 15cm wider and 10cm longer than a double, and the extra length is why kings suit anyone approaching six foot. With 75cm each, a king forgives firmness compromises a double cannot; choose for support first.
The measurement rule
UK king: 150 × 200cm. EU king: 160 × 200cm. US queen: 152 × 203cm. They are not interchangeable — a UK king mattress in an EU frame leaves a 10cm gap. Ours are the UK standard, matched exactly to our king frames. Every size is in the UK bed size guide.
What changes at king size
Width buys freedom: each sleeper gets 75cm, so partners can differ more in firmness needs and both still sleep. What does not improve automatically is motion isolation — a wider surface telegraphs movement further in a poorly built unit, which is why pocket springs matter more, not less, as beds get bigger. And weight: a king mattress is heavy; ours pair with frames designed to carry them, and rotating it is a two-person job worth doing.
Choosing between ours
Structure and alignment — the Arete 1500. Deep memory-foam cushioning — the Laurel Comforto 2500. Natural fillings that breathe — the Laurel Natural 2500. The hotel pillow-top — the Tranquility 3000. All made in king, all with a 60-night free trial and a 5-year warranty — sleep on the decision rather than reading it.
Browse our king size beds, every mattress we make, or the full method in how to choose a mattress.
What size is a king size mattress?
150 × 200cm — 5ft by 6ft 6in, the UK standard king.
Is a king mattress worth it over a double?
If the room takes it, yes — and the 200cm length is the deciding gain for anyone tall. The width is comfort; the length is necessity.
Do king mattresses need a special base?
A king frame — ours are matched exactly to our king mattresses, built to carry the weight.
What about the trial and warranty?
Every mattress carries a 60-night free trial and a 5-year warranty.