The easy guide to mattress sizes in the US and UK

The size of your mattress is just as crucial for your sleep comfort as the firmness rating and the materials it's made from. Our best mattress guide includes every popular size you can buy, from twin to split king, but how do you know which size is right for you? Here we run you through the main US and UK mattress sizes and bed dimensions to help you pick, so get your tape measure ready.

The size you choose makes a big difference to help comfy you feel when snoozing. If your feet are hanging off the edge, or you bump into your partner each time you roll over, your sleep won't be as enjoyable or restful. Thankfully there are plenty of different sizes to pick from, so you should find something to fit your bed no matter how small, large or custom it is. 

For those of you who own an RV, to help you sleep well on the road we also run through the basics of RV mattress sizes. Let’s start now by looking at the main dimensions you’re likely to come across when shopping, whether you’re choosing a great memory foam mattress for all-out comfort, or you’re looking for a long-lasting mattress in a box that works for all sleep styles. 

Mattress sizes and bed dimensions US

Twin size mattress dimensions: 38 x 75 inches (96.5 x 188cm)
This size suits children and younger teenagers, and is an ideal size for growing into. It’s also suitable for bunkbeds.

Twin XL size dimensions: 38 x 80 inches (96.5 x 203.5cm)
This size has the same width as a twin, but is 5 inches longer. This makes it suitable for older teens, adults sleeping solo, or for a smaller bed in a guest room.

Full size mattress dimensions: 54 x 75 inches (134.5 X 190.5cm)
This size is a good option for single sleepers who want a bit more space to stretch out, although it might be a bit of a squeeze for co-sleepers.

Queen size mattress dimensions: 60 x 80 inches (152 x 203.5cm)
Comfortably accommodates couples who don’t require acres of room, and also provides plenty of space for single sleepers who require more room. Queen beds are also available as split models in order to accommodate different firmness needs (so, different firmness levels on either side).

King size mattress dimensions: 76 x 80 inches (193 x 203.5cm)
This roomy option is an excellent choice for two people sleeping comfortably and stretched out. It’s also wide enough to accommodate younger children co-sleeping with their parents. 

Cal king size dimensions: 72 x 84 inches (183 x 213.5cm)
This size is 4 inches narrower and 4 inches longer than a US king size, making it a good solution for taller adults. This size is often offered as a split option so co-sleepers can each choose their own firmness level on either side.

Mattress sizes and bed dimensions UK

Single size mattress dimensions: 36 x 75 inches (92 x 190cm)
This size is ideal for children and teens. It is suitable for bunkbeds, as well as in smaller bedrooms for adults who sleep by themselves. A small single size (which is 4 inches/16cm narrower) is also available.

Small double size dimensions: 48 x 75 inches (123 x 190cm)
A small UK double is wider than a single, but narrower than a double, making it a good choice for solo sleepers who like to stretch out. It’s also a good option for a spare bedroom.

Double size mattress dimensions: 54 x 75 inches (138 x 190cm)
This popular size can comfortably accommodate two adults, and will fit most average-sized bedrooms. At 6ft 3in, it is also a good length for most adults to rest comfortably.

King size bed dimensions: 60 x 78 inches (153 x 198cm)
The UK king size is a good fit for larger bedrooms and provide plenty of space for two sleepers, or a young child co-sleeping with their parents. At 6ft 6in long, it’s also a good option for taller adults.

Super king size dimensions: 72 x 78 inches (183 x 198cm)
At 6ft wide and 6ft 6inches long, this luxuriously large size provides plenty of space and comfort for two adults, or for families with young children. This size also allows taller adults to stretch out comfortably.

A quick look at RV mattress sizes (US)

RV mattress sizes (US)

Getting a good night’s sleep in your RV is crucial for keeping your concentration sharp and focused for driving the next day. As with standard models, there are plenty of RV mattress sizes to choose from:

• Twin – from 28 x 75 inches (71cm x 190.5cm) to 40 x 80 inches (71 x 203cm)
• Truck – from 35 x 79 inches (90cm x 201cm) to 42 x 80 inches (107 x 203cm)
• RV three quarter – 48 x 75 inches (122 x 190.5cm)
• RV full or double – 53 x 75 inches (137 x 190.5cm)
• RV short queen – 60 x 75 inches (152.5 x 190.5cm)
• RV queen – 60 x 80 inches (152.5 x 203cm)
• RV king – from 72 x 75 inches (183 x 190.5 cm) to 72 x 80 inches (183 x 203cm)

There are also various sizes available for bunkbeds – check carefully to make sure you buy the correct size. RV mattresses are available in different types ranging from foam to latex and innerspring. Each type comes with slightly different qualities, so think about what you need for your sleep, as well as what is suitable for an RV. The Brooklyn Bedding Wanderlust (from $276) (opens in new tab) is a popular choice and comes in 10-inch through to 14-inch-deep models.

For instance, memory foam models are excellent for pressure relief and often come with cooling top layers, so hot sleepers needn’t run a mile. Natural latex, meanwhile, is hypoallergenic and resistant to mites and mildew, which is handy in an RV. Innerspring models are more affordable, but they may deteriorate quicker as the coils are prone to rusting in humid air.

The size you buy will depend on the dimensions of the bed platform in your RV. If space allows, you could use a regular bed mattress, but bear in mind that it will probably be used for more than just sleeping on, so make sure it’s durable enough to be in constant use 24 hours a day.

What size mattress do you need?

Finding the right size mattress for your sleep needs depends on many factors, including the following:

• Your weight
• Your height
• Whether you co-sleep with a partner and/or kids
• Your sleeping position
• How big the room is
• The size of your existing bed frame 
• If you allow pets on the bed

The right mattress size will allow you and your co-sleeper to stretch out without feeling squashed or stifled. If the bed is too small, you will not be able to get comfortable, which will soon put strain on your posture and lead to aches and pains. Even the best pillow for sleeping won't save you from this fate. On the other hand, if it's too too large it might take up too much space in the room, and it will be trickier to transport, flip or rotate.

The ideal mattress for sleeping should be approximately six inches longer than the tallest individual sleeping in it, and allow sufficient space above the head. In terms of width, each individual should be able to rest comfortably with hands behind their heads and elbows out flat without knocking into their partner.

If you sleep on your front or back you will be more fully extended than a side sleeper, so anyone taller than 6ft should choose a mattress longer than 80 inches (203cm). As for width, co-sleepers should go no smaller than a US queen/UK king, to ensure there is plenty of room for each person to sleep in the position that is most comfy for them.

There are various times of the year when you'll be able to find good mattresses for less, and these include Memorial Day, Labor Day, and when the Black Friday mattress deals arrive each November.

Essential care and cleaning tips 

Once you have found your dream bed, you’ll want it to last for as long as possible. As well as regularly changing the sheets, you should also make sure the mattress is occasionally aired and deep-cleaned too. Our feature on how to clean a mattress explains more, including how to clean up accidental spills. Wondering 'why is my mattress yellow?' We have you covered for answers there too. 

To really make sure it stays cleaner for longer (and therefore lasts longer and saves you money in the long-term), a good mattress protector is an excellent way to protect against spills, sweat, allergens and dust mites. The best mattress toppers also offer protection, but really they provide an extra layer of comfort, whether that’s an extra-soft pillowy top or a cooling layer for hot sleepers.

Finally, it’s good practice to rotate your mattress every few months or so. This ensures it stays supportive and in good condition for longer, with no unevenness or worn-out patches. Find out more in our feature answering how often should you rotate a mattress.

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