If you have ever bought a duvet cover online and found it sags at the sides or will not close over the duvet, you are not alone. UK bedding sizes look simple until you start measuring, and the numbers on the label are not always the numbers you need.
This is a short guide to getting it right first time.
The four UK duvet sizes
British bedding follows four standard duvet sizes. These are the duvet itself, not the bed.
| Size | Duvet | Usual bed |
|---|---|---|
| Single | 135 × 200 cm | 90 × 190 cm |
| Double | 200 × 200 cm | 135 × 190 cm |
| King | 225 × 220 cm | 150 × 200 cm |
| Super King | 260 × 220 cm | 180 × 200 cm |
Notice that a Double duvet is 200 cm wide while a Double bed is only 135 cm. That extra width is the overhang, and it is why you cannot size a duvet from your mattress alone.
Measure the duvet, not the bed
This is the single most useful habit. A duvet cover has to fit the duvet going inside it, and duvets vary more than beds do. Two people can both own a "king" duvet and have covers that differ by ten centimetres.
Lay the duvet flat, measure edge to edge across the widest point, then top to bottom. Write both numbers down. That is what you are shopping for.
Why imported sizes rarely match
A great deal of bedding sold in the UK is manufactured abroad, and other countries use different standards.
American sizing runs Twin, Full, Queen, King and California King. None of these map cleanly onto British sizes. An American Full cover is roughly 224 cm wide, which sits between a UK Double at 200 cm and a UK King at 225 cm. Order it expecting a Double and you will have 24 cm of loose fabric at the sides.
European and Asian manufacturers often cut covers longer than the British standard, sometimes by 40 cm or more. That is not a fault. It gives more overhang at the foot of the bed, which some people prefer and others find untidy.
The lesson is the same either way: trust the centimetres, not the name. If a listing gives you a size name without dimensions, ask before you buy.
How much slack is acceptable
A cover should be the same size as your duvet or slightly larger. Slightly larger is fine and often intentional. Smaller is not: you will not get the duvet in, and forcing it stresses the seams.
As a rough guide, up to about 10 cm of extra width sits unnoticed. Beyond 20 cm the cover starts to look loose and the duvet shifts inside it overnight. Extra length is more forgiving than extra width, because it simply hangs at the foot of the bed.
Pillowcases
The UK standard pillowcase is 50 × 75 cm, which suits a standard British pillow. You will also see Oxford pillowcases, which have a flat fabric border of five to seven centimetres around the edge, and Square or Continental cases at 65 × 65 cm, used mainly for propping up against a headboard rather than sleeping on.
A case a centimetre or two under the standard is normal and will still fit. A case cut for a 40 × 80 cm European pillow will not.
A note on thread count
Thread count is the number of threads woven into a square inch of fabric. Higher is often marketed as better, but past a point the figure is achieved by twisting several thin strands together and counting each one, which produces a heavier fabric rather than a finer one.
Between 200 and 400 in a good long-staple cotton will outlast and outperform a much higher number in a poor one. Weave matters more than the figure: percale is crisp and cool, sateen is smoother and warmer to the touch.
Treat thread count as one detail among several, not as a score.
Before you order
- Measure your duvet flat, width first, then length.
- Check the listing gives dimensions in centimetres, not only a size name.
- Allow for a tolerance of one to three centimetres on anything measured by hand.
- Check how many pillowcases are included, and their size.
- Check whether a flat or fitted sheet is part of the set. Often it is not.
Five minutes with a tape measure saves a return, and a return on bedding is nobody's idea of a good afternoon.