Mattress Guides

Single vs. Twin Bed Size: What’s the Difference?

By Angela Nault, August 24, 2022

Single and twin beds are terms used interchangeably. Both beds are 38 inches wide and 75 inches long. While they’re exactly the same size, they have different intended uses.

Single beds are meant to sleep one person. Twin beds, on the other hand, are meant to be a pair of two matching single beds. Despite this, twin beds are often sold separately.

Twin and single beds are best for singles or children sharing a bedroom. One twin or single bed can fit a bedroom no smaller than 7 by 10 feet or 10 by 10 feet for a pair of twin beds in one room.

What’s a Single Bed?

Single beds are intended to sleep one person. They are narrow beds built to fit in small bedrooms, such as a child’s bedroom or a studio apartment. It’s the smallest standard bed size after cribs and cots specially designed for children.

What’s a Twin Bed?

A twin bed is technically one part of a matching set of two single beds, thus the name “twin” bed. The term originated when hotels placed two single beds with a nightstand between them in one guest room, and called it a twin room.

One twin bed sleeps just one person. A set of twin beds, on the other hand, sleeps two people.

What’s a Twin XL Bed?

Twin beds have a slightly larger counterpart known as the twin XL. It’s the same width as a standard twin or single bed, but it’s 5 inches longer to suit adults, growing children, and teenagers. Twin XLs are quite common in dorm rooms, as well, since they are narrow yet accommodate a wider range of heights than a twin or single bed.

Standard twin beds are quite short, so a twin XL provides extra height for different sleepers, such as tall adults or growing children and teens.

Furthermore, two twin XLs pushed together make one king bed. So, for couples who have different mattress preferences but share one bed may consider using two twin XLs. This bed can also be paired with a split adjustable base, so couples can adjust their incline to their needs as well.

What Makes Single and Twin Mattresses Different?

At the end of the day, twin and single beds aren’t too different. They fit the same frames, foundations, and bedding. People once used the term “single bed” more frequently, though now this terminology is mainly used in Europe.

When shopping for a 38 by 75 mattress and its accessories in the United States, you likely will only see it referred to as a twin.

Twin beds are usually sold as one bed, so technically, your bed doesn’t become a “twin” unless you buy two single beds. Regardless, the term twin still stands and is predominantly used to describe single beds.

Who Should Buy a Single or Twin Bed?

While single and twin beds can technically fit into nearly all bedrooms, they are best used for:

  • Children: Single and twin beds are mostly used by growing children as they’re shorter and have smaller bedrooms than most adults. If you have multiple children sharing a room, two twin beds can fit comfortably in one room and give your children enough floor space to play.
  • Adults under 6 feet tall: Twin and single beds are 75 inches long, so if you’re shorter than 6 feet and sleep alone, you should be able to sleep comfortably on a twin or single bed. If you’re taller than 6 feet, consider a twin XL mattress for extra length.
  • Guests: If you have a guest room, consider purchasing multiple twin or single beds instead of one full or queen bed. That way, if you have multiple guests, they won’t have to sleep on one bed.
  • Small living spaces: If you live in a small home, studio apartment, or in a dorm, a twin or single bed provides enough sleeping space without taking up too much room. Twin and single mattresses are also compatible with bunk beds and trundle beds, so you can sleep two people comfortably while only using the storage space of one bed.
  • Vacation homes: Twin and single beds are budget-friendly options for those furnishing a vacation home or rental property. However, queen and king beds are also popular since they accommodate couples and can fit more sleepers.


Should I get a twin or full bed?

A full bed is 54 inches wide and 75 inches tall. It’s also called a double bed because it can fit two sleepers. Although full beds can technically sleep two adults, they are a bit too narrow and short for most people.

A full bed would be best for a single sleeper who is less than 6 feet tall and who wants to stretch out more than they could on a twin bed. Full beds fit well in small rooms and are a more affordable alternative to a queen bed.

If you need a more narrow sleeping space and are a single sleeper, a twin bed works better than a full bed.

What size bed do two twins make?

Two standard twin beds pushed together don’t equal any other standard mattress size. Two twins are as wide as a king bed, but shorter. A standard king bed is 76 by 80 inches, while two twin beds are 76 by 75 inches.

King beds are designed for adults, couples, and families who co-sleep, and two twin beds may be too short for these purposes. In addition, bed accessories are rarely made to fit two twins pushed together. King bed accessories and foundations would not suit two twin beds, either.

A split king mattress is two twin XL beds pushed together.

What is a youth bed?

Youth beds, also referred to as junior beds, are slightly smaller than a standard twin, though they are larger than cribs or toddler mattresses. They are 33 inches wide and 66 inches long and designed for children outgrowing their crib and toddler beds.

Youth beds are similar to twin beds, but they are not in high demand. When transitioning your child from a crib to a bed, you might as well purchase a standard twin as opposed to a youth bed. Your child will grow into their twin bed before you know it.

When should I move my child to a twin bed?

If your child is roughly 3 to 4 years old or at least 3 feet tall, it’s time to get them a twin bed. Cribs and toddler beds are too small for a growing child and, once you upgrade to a twin bed, your child can use it for a long period of time.

When shopping for a twin bed for your child, try choosing one that’s lower to the ground so it’s easy for them to get in and out of bed (reducing the risk of falling).

Can my child go from a crib to a twin bed?

Yes, you can most definitely transfer from a crib straight to a twin bed. Some parents may transition their child from a crib to a toddler bed or use a crib-toddler bed combo, though they’re essentially the same size. And if your child is already outgrowing their crib, it would be a waste of money to buy a bed the same size as their crib. At this point, it’s best to just make the switch to a twin bed.

If you’re hoping your child will use their first grown-up bed for years and years to come,  consider upgrading them to a twin XL for an additional 5 inches of height.


While there’s no size difference between twin and single beds, the beds technically serve purposes. Twin beds are made to be sold in a pair, though nowadays, they’re mostly sold by themselves, while single beds are meant to be sold individually. Regardless, twin and single beds are great for singles under six feet tall, siblings sharing a bedroom, or guest rooms.

If you’re based in the United States, chances are you won’t see twin beds referred to as single beds, and vice versa for international readers.

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