Twin vs. Full: What’s the Difference? 

Key Takeaways

  • Size and Suitability: Twin mattresses, measuring 38 by 75 inches, are ideal for children, small guest rooms, and dorms, offering affordability and versatility. Full mattresses, measuring 54 by 75 inches, provide more sleeping space for single adults and growing teens but are typically too narrow for two people to sleep comfortably.
  • Room and Budget Considerations: Twin mattresses fit well in smaller rooms (minimum 7 by 10 feet), making them a budget-friendly option for children’s rooms and tight spaces. Full mattresses require larger rooms (minimum 10 by 12 feet) and, while more expensive, can be a longer-term investment for growing children and single adults.
  • User Needs: Twin beds are perfect for younger children and teens transitioning from cribs, while full beds offer extra space for single sleepers and can accommodate teens into adulthood. Both mattress types are available in XL versions for taller individuals needing extra legroom.

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If you’re shopping for a new bed, perhaps for a child or guest bedroom, you might be stuck between two small mattress sizes, twin or full size. Despite being the smallest standard mattress sizes, twin and full mattresses vary in functionality and comfort.

Choosing a mattress size often comes down to cost, who’s using the bed, and the space available. In our article, we break down the differences between twin and full mattresses to help you make a decision.

Dimensions of Twin and Full Mattress:

FeatureTwin BedFull Bed
Dimensions38 inches wide x 75 inches long54 inches wide x 75 inches long
Area2,850 square inches4,050 square inches
Width per Person38 inches (single sleeper)27 inches (for two sleepers)

Twin Mattresses

The twin mattress is the smallest standard-sized mattress, measuring 38 by 75 inches, and best suits individual sleepers. The title “twin” refers to how single mattresses were originally sold in pairs. However, most twin mattresses are now sold separately, despite still being called “twin” beds.

Most twin beds cost roughly between $100 to $1300, depending on the materials and included sleep technologies. They’re super versatile and can be used as:

Naturally, you can also use twin mattresses with standard bed frames. Twin mattresses are great for children, teens, toddlers who have outgrown their cribs, and single adults. However, some adults might find twin beds to be a bit short and narrow.

For sleepers in need of extra legroom, twin mattresses are available in a longer version called the twin XL. At 38 by 80 inches, they work well for teens, tall adults, apartments, and dorms.

Pros of a Twin Mattress

  • Affordable
  • Lightweight
  • Ideal first bed for a child
  • Fits in small spaces

Cons of a Twin Mattress

  • Can be too small for some adults
  • Only sleeps one person
  • Children and teens can grow out of the bed quickly

Full Mattresses

Full mattresses are 15 inches wider than a twin, measuring 53 by 75 inches. They’re also known as double beds, just as twin beds are called singles, though two single beds don’t equal one double bed. Full mattresses typically cost between $500 to $3000.

A full mattress is a good compromise if you can’t afford a queen size mattress, but need a bed larger than a twin. Unlike a queen, however, full mattresses are best for one person. Two people can technically fit on a full bed, though they’ll only have 26.5 inches of width to themselves, or the equivalent of a crib.

Full mattresses work well for guest bedrooms, apartments, or a child’s bedroom. Many growing teens and children use full beds instead of twins for extra space. Some adults can use full beds comfortably, though others might find full mattresses too short.

Just like a twin mattress, full mattresses are also available as full XLs. A full XL is five inches longer than a standard full mattress (53 by 80 inches) and accommodates taller sleepers and narrow, but long bedrooms.

Pros of a Full Mattress

  • Extra sleeping space for single sleepers
  • Good for adults and growing children or teens
  • More affordable than a queen or king mattress
  • Fits in smaller master bedrooms

Cons of a Full Mattress

  • Can be too short for some adults and teens
  • Usually too narrow to sleep two people comfortably
  • More expensive than a twin mattress

How to Choose Between a Twin and Full-Size Mattress

The main determining variables when choosing between a twin and full mattress are your bedroom size, your budget, and who the bed is for. After all, you likely wouldn’t buy a child a king mattress or put one twin mattress in a 13 by 13-foot room.

a. Bedroom Space

Your bedroom size is important since if your mattress is too big, it might not leave space for other furniture in the room, such as end tables, dressers, or mirrors. At the same time, a small bed in a large bedroom might make the room feel a bit empty.

Your bedroom should be at least 10 by 12 feet for a full bed and at least 7 by 10 feet for a twin bed. If you’re trying to sleep multiple people in a 7 by 10-foot room, a bunk bed is a great option and works with most twin beds.

FeatureTwin BedFull Bed
Minimum Room Size7 x 10 feet10 x 12 feet
Ideal Room Size9 x 10 feet or larger12 x 12 feet or larger
OccupancySingle sleeperSingle sleeper or two small sleepers
Best ForChildren, small guest rooms, dormsSingle adults, guest rooms, teenagers

b. Users

Determining who will be using the bed is essential when deciding what mattress size you need. Both full and twin mattresses are best suited for one person, though a full can technically squeeze in two people if needed.

Twin mattresses are useful for children transitioning from their cribs, though some parents might decide to upgrade their child straight to a full bed so it can be used well into their teen years. Teens and average-sized adults can also use twins, though if the bed is too narrow, they might prefer a full bed instead.

Taller teens and adults likely won’t be comfortable on a twin or full mattress, so they should opt for larger mattresses, such as a twin XL, full XL, or a queen.

c. Budget

Choosing a mattress sometimes comes down to what you can afford to purchase. While full mattresses and their accessories cost more than twin beds due to the extra materials, they might be useful for a longer period of time.

Frequently Asked Questions

When should children transition to a “big-kid” bed?

Usually, when your child is between the ages of 18 months and 3 ½ years old, they can start transitioning out of their crib and into a full-sized bed. If your child expresses interest in a “big-kid” bed or starts climbing over the rails of their crib (this can become a safety concern), it’s time to look for a bigger bed.

There are some toddler-sized beds, though your child would only be able to use it for a few years at most, so you might prefer a twin or a full bed. A full bed can seem a bit large for your child right now, but in a few years, the extra space will likely be appreciated and you won’t have to worry about changing their bed multiple times.

How thick should a child’s mattress be?

Since children are so small and light, they don’t need the same mattress thickness average adults need (10 inches or more). An 8-inch mattress provides enough cushioning and support for most children.
There are some toddler-sized beds, though your child would only be able to use it for a few years at most, so you might prefer a twin or a full bed. A full bed can seem a bit large for your child right now, but in a few years, the extra space will likely be appreciated and you won’t have to worry about changing their bed multiple times.

Do two twin mattresses make a king mattress?

Two twins pushed together are as wide as a standard king mattress, but not as tall, measuring at 76 by 75 inches. Two twins together don’t make a standard mattress size, so if you choose this set-up, it might be challenging to find proper accessories, such as the bed frame and sheets.

Two twin XL mattresses pushed together make a king mattress, and this is a standard model called a split king. Split kings are primarily used for couples with different firmness preferences, and they work well with adjustable bases.

Is there a big difference between a full mattress and a queen mattress?

There’s only a few inches of difference between full and queen mattresses, though this significantly affects the functionality of both mattresses. A queen mattress is 60 by 80 inches, 7 inches wider, and 5 inches longer than a full mattress (53 by 75 inches).

Queen mattresses can comfortably sleep two people and provide extra legroom for tall sleepers. Full mattresses are best suited for single sleepers such as children, teens, and average-height adults. Since a queen mattress is larger than a full mattress, the mattress and any accessories cost a bit more and you need a slightly larger bedroom to accommodate them (at least 10 by 14 feet).

What mattress size is best for a guest room?

When choosing a mattress size for a guest bedroom, consider who you plan on having to visit, how long they’ll be there, and how often they visit. Say you have one or two guests once a year, do you even need an entire bedroom dedicated for them? If not, you might consider using a daybed or Murphy bed, as they’re space-conscious.

Determine how large the guest room is, as well as any other furniture in the room, before settling on mattress size. Here’s a quick list of common bedroom sizes and the bed sizes best suited for them:

  • 7 by 10 feet: Twin
  • 10 by 12 feet: Full
  • 10 by 14 feet: Queen
  • 13 by 13 feet: King
  • 14 by 12 feet: California King

With larger rooms, you don’t need to use the biggest bed possible. You can always use multiple twin beds in or two full beds in large bedrooms so guests don’t have to share one bed.


Consider your needs when choosing between a full or twin mattress, such as your space and the age and size of the person using the mattress. Price is a crucial factor when shopping, and full beds and their accessories are ultimately more expensive than a twin bed and its accessories. However, you might find a full mattress will be usable for longer, especially with growing children.

This article is for informational purposes and should not replace advice from your doctor or other medical professional.

Sarah Anderson, Certified Sleep Science Coach Sarah Anderson

Sarah Anderson is a sleep, health, and wellness writer and product reviewer. She has written articles on changing and improving your sleep schedule, choosing the right mattress for chronic pain conditions, and finding the best pillow for you. Sarah Anderson has her Bachelor of Arts degree from Arizona State University in Journalism and Mass Communications. Prior to working for Zoma, she wrote for a variety of news publications. Sarah's work has been featured on Bustle, PureWow, and other publications.

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