Sleep Product Tester
Austin is a professional writer and researcher who has covered sleep science and sleep products for over a decade.
Understanding the world of mattress sizes can be confusing. Some terms mean one thing in the United States, and something else entirely in the rest of the world. Other terms, like “single” and “twin”, mean the same thing, but are both commonly used.
Single and twin are two terms for the same bed size. There is no difference between the two, and both terms are often used interchangeably.
“Single” used to be the more popular terminology, but today, “twin” is more commonly used. This is true in most countries, although some nations still prefer the term “single”. The term originally came about because hotels often placed two single beds – “twin” single beds – in the same room.
Some twin beds are designed to be bought and used in pairs. However, this is not necessary, and the dimensions of both twin and single beds are identical.
The twin bed size is generally 38 inches by 75 inches (sometimes 39 inches by 75 inches). This makes it the smallest mattress, outside of beds designed specifically for cribs and small children. It’s certainly designed for only one sleeper.
Twin XL beds are a different size altogether, which can create some confusion. A twin XL is 38/39 inches wide by 80 inches long, giving it an extra 5 inches of legroom over the standard twin. Twin XL is a better choice for college students and adults over 6 feet tall. See our twin vs twin XL comparison for details.
We typically recommend twin beds for children and teens, and occasionally for single adults who don’t need a lot of space. Everyone else will be better off with a larger mattress.