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You’d be forgiven for thinking there are only three adult mattress sizes – single, double and king. But adult mattresses actually come in 10 different sizes.
This should make it easier to buy a mattress that's just right for you, but it also increases the risk of buying a mattress only to find it doesn’t quite fit your bed frame or bed sheets.
While a bigger mattress may help you sleep, it won't help nearly as much as buying a mattress that provides excellent long-lasting support for your body size and sleeping position.
The table below shows the full range and dimensions of adult mattresses available to buy in the UK.
|Name||Size in centimetres||Size in feet and inches|
|Small single mattress||75cm x 190cm||2'6" x 6'3"|
|Single mattress||90cm x 190cm||3' x 6'3"|
|Euro single mattress||90cm x 200cm||3' x 6'6"|
|Small double mattress||120cm x 190cm||4' x 6'3"|
|Double mattress||135cm x 190cm||4'6" x 6'3"|
|Euro double mattress||140cm x 200cm||4'9" x 6'6"|
|King size mattress||150cm x 200cm||5' x 6'6"|
Also known as a narrow single mattress, this is the smallest adult bed you can buy. It measures 75x190cm (approximately 2’6” x 6’3”). So while it’s the same length as a standard single – and therefore long enough for most adults – it’s 15cm narrower.
Small single mattresses are often used for children, but they’re also a good option for a box room or study that you want to turn into a small guest bedroom.
There’s a reason the standard single mattress is still the fourth most popular mattress size with Which? Connect panel members.* Unless you’re a lot taller or broader than average, the single mattress is the right size for a single adult.
It’s 90x190cm (approximately 3’ x 6’6”), so there should be enough space to roll into a different sleeping position during the night.
If you’re looking for a single mattress but find that your feet tend to dangle over the edge of the bed, you may want to consider a European single mattress.
It’s 90x190cm (approximately 3’ x 6’6”), making it 10cm longer than a standard single.
If you thought a queen-size bed was somewhere between a standard double and a king, you’re not alone. In actual fact, it's smaller than a double. Just 2% of our Which? Connect panel members own one, according to our latest mattress survey*.
A queen-size mattress is the same length as a standard double, but it’s 15cm narrower, hence why it’s also known as a small double mattress. It measures 120x190cm (approximately 4’ x 6’3”)
Two adults will find a small double mattress pretty snug, but it could be just the thing for a small bedroom or if you sleep alone but like to stretch out.
Double mattresses measure 135x190cm (approximately 4’6” x 6’3), are the second most popular mattress size* and tend to look well-proportioned in most bedrooms, and this is the mattress size we use to test.
They’re generally long and wide enough to accommodate two average-sized adults but there may not be much wiggle room. Ideally, you and your partner should both be able to lie on your back with your hands behind your head without your elbows touching each other or the edge of the bed.
If you’re a restless sleeper or larger than average, you may want to consider a slightly larger mattress, provided your bedroom and bed frame is big enough.
If a double mattress feels a tad too cosy, but your bedroom isn’t quite big enough for a king, you’ll want to consider a European double mattress. They measure 140x200cm (approximately 4’9” x 6’6”).
But they’re less widely available than standard doubles, so you may need to shop around. International manufacturers, such as Ikea, tend to stock them, but they’re less common at high-street retailers.
Nearly half of Which? members own a king size mattress, making it the most popular size.* This size is widely available and, while a king size can be a fair bit more expensive than a double, it will provide a lot more sleeping space. A king size mattress is 150x200cm (approximately 5’3” x 6’6”).
As with the European versions of the single and double mattress, the Euro king is a fraction bigger than a standard king. It’s 160cm x 200cm (approximately 6' x 6’6”).
The length is the same, but it’s 10cm wider, giving you a touch more space to roll over and switch sleeping positions during the night.
A super king mattress is basically two standard single mattresses stuck together. In fact, some super king mattresses are literally just that, with a growing number of couples opting for two different singles that zip together to form a super king. This means each person can get the firmness that suits them. 11% of Which? members own a super king size mattress*.
A super king mattress measures 180x200cm (approximately 6’ x 6’6”).
An emperor mattress is the biggest you can get and is basically an enormous square. Measuring 200x200cm (approximately 6’6” x 6’6”), it’s easily big enough for two larger-than-average adults.
Not many mattress brands make mattresses this big, so you may need to shop around and be prepared to spend significantly more.
Confused by Ikea mattress sizes? You’re not alone. Ikea sells both double mattress and Euro double mattress sizes.
If you bought a bed from Ikea some time ago, you may have a European double size, so before you buy a new mattress, it’s worth checking what size Ikea bed you have, before you head to the shops.
The mattresses are sometimes listed separately on the Ikea site, so try searching by mattress name and then check you’ve chosen the correct size mattress for your bed.
Or, on some mattress pages on the Ikea website, there’s a ‘choose size’ box – so make sure the correct size is chosen here. Our advice would be to check what size you are buying on the website before forking out any cash.
All the Ikea mattresses we test are standard UK double mattress size (135cm x 190cm), but the thickness can vary. Our lab experts check the dimensions of all the mattresses we test, so we can see any larger or smaller than this size.
More than three in four Which? members sleep on either a king size or a double mattress, and that’s been the case for several years.
More recently, super king mattresses have become the third most popular mattress size.
*According to an August 2021 survey of 2,851 Which? members.
No matter how much you like the idea of stretching out on a huge new emperor mattress, you need to consider how the bed will look in your bedroom.
A huge bed in a small bedroom can look out of place, as can a small bed in a huge room.
A ratio of around 1:3 between bed and bedroom is sometimes said to look best, but depending on the size of your bedroom that can be difficult in practice. Following this advice would mean, for instance, that for a king size bed –1.5x2m – you'd need a 6x8m bedroom.
At the very least, you should aim for a space of 30 inches between the sides and bottom of the bed and your nearest wall or piece of furniture. And don't forget to check where you plug sockets are, so you don't inadvertently block access with a bed that's too big.
|Name||Bed size||Fitted sheet size||Flat sheet size||Duvet size|
Sheet and duvet sizes can very by brand, so always double check dimensions.