Updated 9 September 2026. Buying bedding is easier when you separate three measurements: your mattress, your duvet and the bedding itself. A UK double mattress and a double duvet are very different sizes, and a fitted sheet’s listed fabric dimensions can differ from the mattress it is designed for.
Common UK mattress sizes
| UK size | Mattress |
|---|---|
| Single | 90 × 190 cm |
| Small double | 120 × 190 cm |
| Double | 135 × 190 cm |
| King | 150 × 200 cm |
| Super king | 180 × 200 cm |
These common UK dimensions are also listed in John Lewis’s bed linen buying guide. Measure your own mattress, especially if it is an EU size, an older model or a custom design.
Match the cover to your duvet
Read the duvet’s label and measure it flat. Common UK duvet dimensions are single 135 × 200 cm, double 200 × 200 cm, king 225 × 220 cm and super king 260 × 220 cm. A king duvet is not 225 × 200 cm. Duvet-cover dimensions can vary between brands, so check the product’s measurements as well as its size name.
For comparison, Scooms’ size guide separates duvet sizes from cover and sheet sizes. This distinction matters more than matching the word “king” on two labels.
Sloth bamboo bedding set measurements
The table below follows our current Sloth size guide. These are the published bedding measurements, rather than a second set of mattress standards. All measurements are approximate.
| Set size | Duvet cover | Fitted sheet | Pillowcase |
|---|---|---|---|
| UK double | 200 × 200 | 140 × 190 + 35 | 50 × 75 |
| UK king | 225 × 220 | 150 × 200 + 35 | 50 × 75 |
| UK super king | 260 × 220 | 180 × 200 + 35 | 50 × 75 |
The “+35” refers to the fitted sheet’s depth allowance. Our double sheet is listed as 140 cm wide; that does not change the common UK double mattress measurement of 135 cm. If you are uncertain about your particular mattress and topper, contact us with their measurements before ordering.
How to measure before ordering
- Measure the mattress across the top, then from head to foot.
- Measure its depth, including any topper you plan to keep under the sheet.
- Check the duvet’s width and length separately.
- Measure your pillows and compare them with the pillowcase dimensions.
- Compare all four measurements with the product size guide.
What comes in a Sloth bedding set?
Each Sloth bamboo bedding set includes a duvet cover, a fitted sheet and two pillowcases. The bedding is white with a choice of piping colours; it does not include a duvet or pillows. Choose your size and piping colour on the product page to see current availability.
Common sizing questions
Is a UK king the same as a US king?
No. Country size names are not interchangeable. Compare measurements in centimetres rather than relying on the label.
Can I use a larger duvet on a smaller bed?
You can choose extra overhang, but the cover still needs to fit the duvet. Check the fitted sheet separately against your mattress.
Does bedding change size after washing?
Follow the product’s care guidance. Sloth’s care instructions explain that the bedding arrives slightly oversized and softens and shrinks slightly with initial washing.