UK bedding is sold by the mattress size it fits: single (90 x 190 cm), double (135 x 190 cm), king (150 x 200 cm) and super king (180 x 200 cm). Duvet covers are cut larger than the mattress, so match the cover to your duvet size, not your bed, and check your fitted sheet depth against your mattress height before you buy.
Buying bedding in the UK looks simple until a duvet cover arrives that swamps your duvet, or a fitted sheet that pings off the corner at 3am. Sizes are named after the bed, but each item (duvet cover, fitted sheet, flat sheet, pillowcase) has its own dimensions, and they vary slightly between brands. This guide gives you the numbers, a quick way to measure, and the mistakes worth avoiding.
All Cottsbury measurements below come from our own product specification and size chart pages, in centimetres. Measurements can vary by a few centimetres between batches and between brands, so always check the size chart on the product page you are buying from.
UK mattress sizes at a glance
| Bed size | Mattress (W x L, cm) | Typically sleeps |
|---|---|---|
| Single | 90 x 190 | One person, children's rooms, guest rooms |
| Small double | 120 x 190 | One adult wanting extra room |
| Double | 135 x 190 | One adult, or two in a snug fit |
| King | 150 x 200 | Two adults |
| Super king | 180 x 200 | Two adults, plenty of room |
Most UK retailers use these figures. Some list super king at 180 cm wide and a few at 183 or 184 cm, so check your actual mattress label rather than relying on the name alone.
Duvet cover sizes
A duvet cover should be close to the size of the duvet inside it. Too big and the duvet bunches into the corners; too small and you will be fighting to close it.
| Size | Cottsbury duvet cover (W x L, cm) |
|---|---|
| Single | 135 x 200 |
| Double | 200 x 200 |
| King | 230 x 220 |
| Super king | 260 x 220 |
Our organic cotton duvet covers close with concealed coconut-shell buttons, so a snug fit matters more than with a zip. If you sit between two sizes (a lot of double beds use a king duvet for extra drape), buy for the duvet you own.
Fitted sheet sizes and depth
Fitted sheets are the item that most often goes wrong, because the width and length are only half the story. Depth matters just as much. Measure from the top of your mattress to the base, including any topper.
| Size | Cottsbury fitted sheet (W x L x depth, cm) |
|---|---|
| Single | 90 x 190 x 30 |
| Double | 137 x 190 x 30 |
| King | 150 x 200 x 30 |
| Super king | 180 x 200 x 30 |
Our fitted sheets have an elasticated border for mattresses up to 30 cm deep. If your mattress plus topper is deeper than that, look for a deep-fit sheet instead. Standard depth in the UK is often around 25 to 30 cm, with deep options up to 35 to 40 cm.
Flat sheet and pillowcase sizes
Flat sheets are cut generously so they can be tucked under the mattress. Our flat sheets are listed at roughly single 180 x 270 cm, double 227 x 270 cm, king 265 x 280 cm and super king 295 x 280 cm in the size guide.
Standard and Oxford pillowcases are both 50 x 75 cm. The difference is the finish: an Oxford pillowcase has a flat border (flange) around the edge, while a standard case has a plain edge.
How to measure for bedding in four steps
- Measure your mattress: width, length and depth, in centimetres, at its widest points.
- Include toppers: add the topper's height to the mattress depth before choosing a fitted sheet.
- Check your duvet: the label on the duvet shows its size. Buy the cover to match.
- Compare with the size chart: a size name is a guide only, so compare your measurements with the retailer's chart.
Which bedding size do you need? Common situations
- Double bed, two people who share a duvet: a king duvet cover gives extra overhang so nobody is left exposed.
- Small double bed: there is no dedicated small double range in most shops. Buy double bedding and check the fitted sheet width, which may be loose.
- Two single beds pushed together: use two single sets, or one super king duvet with two single fitted sheets.
- European or non-standard beds: bed frames bought abroad may not match UK sizes. Measure before you buy.
- Sets versus separates: a bedding set pairs a duvet cover, fitted sheet and pillowcases in one go, which takes the guesswork out. Separates let you mix sizes and colours.
Does size change how bedding feels?
Organic cotton can shrink slightly on the first washes, as natural fibres do. Our sateen is made to be washed on a gentle cycle at 30 degrees with a plant-based detergent, and line dried where possible. Washing at lower temperatures and avoiding a hot tumble dry keeps shrinkage low. If you are between sizes and care about a perfect fit, go up rather than down.
The fabric behind these sizes is 100% GOTS-certified organic cotton in a 300 thread count sateen weave, made in a Fairtrade-certified factory in India. If you are still choosing a material, our guide on percale versus sateen explains the difference.
Frequently asked questions
What is the difference between a king and a super king bed in the UK?
A UK king is typically 150 x 200 cm and a super king is 180 x 200 cm. The super king is 30 cm wider, which is enough for two adults to sleep without crowding each other.
What size duvet cover fits a double bed?
A double duvet cover (200 x 200 cm) fits a standard double duvet. Many couples prefer a king cover (230 x 220 cm) on a double bed for extra overhang.
Is a double fitted sheet 135 cm wide?
The mattress is 135 cm wide, while our double fitted sheet is cut at 137 cm to allow for a snug, elasticated fit. Sizing varies a little between brands.
How deep is a standard fitted sheet?
Standard fitted sheets usually fit mattresses up to about 25 to 30 cm deep. Ours fit up to 30 cm. Deep-fit sheets are made for thicker mattresses or toppers.
Can I use a king duvet cover on a super king bed?
You can, but it will leave little overhang. A super king duvet cover (260 x 220 cm) is designed to cover a super king bed properly.
Are pillowcases the same size across the UK?
Standard UK pillowcases are usually about 50 x 75 cm, although European square pillowcases are a different shape. Check which type your pillows are before ordering.
Ready to choose? Browse our organic cotton bedding collection and use the size chart on each product page to confirm your fit.