US and UK bed size differences are outlined below. Note that the measurements used in other countries may not follow either of these specifications.
Twin / single beds are 75″ long and 39″ wide. The sleeping space is 39″ x 75″, good for one sleeper. This is a small bed and easy to move around. It is frequently found in guest rooms. The twin extra long bed is 39″ wide and 80″ long. The sleeping space is 39″ x 80″, good for one person. This bed is longer than the twin / single. The only drawback is that linen for it can be hard to locate.
A full / double bed is 75″ long and 54″ wide. The sleeping space person is 27″ x 75″, good for two people. However, the space is sufficient only for two small or average size adults. Two physically large people will have a hard time sleeping on it.
A queen size bed is 60″ wide and 80″ long. The sleeping space is 30″ x 80″ per person (good for two people). This is one of the most popular bed choices in the US for couples. A standard king size bed is 80″ long and 76″ wide. This bed is for two people. Each will get a sleeping area of 38″ x 80″. Given the bed size differences between king and queen beds, the former is more suited for couples who need lots of space.
A California King bed is 84″ long and 72″ wide. There is room for two sleepers, with each getting 36″ x 84″ of sleeping space. This is a variation of the king size bed. It is longer but narrower than a regular king bed.
UK Bed and Mattress Dimensions
A single bed in the UK is 36″ wide and 75″ long. The sleeping space is 36″ x 75″ (for one person). This is equivalent to the US twin/single. The double is 75″ long and 54″ wide. It is for two people each with a space of 27″ x 75″. It is one of the most common beds in the UK. A king size bed is 78″ long and 60” wide. It is as wide as the US queen bed but shorter. A super king bed is 78″ long and 72″ wide. There is 36″ x 78″ space for each sleeper.
These bed size differences are general guidelines. Some companies make their beds slightly longer or shorter than the figures stated here.