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

Last Updated On January 15th, 2024
Single vs. Twin Bed Size: What’s the Difference?

Key Takeaways

  • Single vs. Twin Terminology: The terms “single” and “twin” are often used interchangeably to refer to a mattress measuring approximately 38 inches by 74 inches, with some slight variations in dimensions. Originally, “single” referred to one mattress, while “twin” referred to one of two small beds in a pair, typically found in children’s rooms.
  • Changing Terminology: Over time, the term “twin” has become more commonly used to describe a single mattress, even when referring to just one mattress and not part of a pair. This shift in terminology has led to some confusion among shoppers.
  • Choosing the Right Mattress Size: When choosing the right mattress size, consider factors like room space, budget constraints, the number of sleepers in the bed, and personal preferences to ensure a comfortable and suitable sleeping arrangement.

When shopping among the different mattress sizes, some people grow confused by the idea of a single size mattress. Is it smaller than a twin mattress, they may wonder?

Actually, “single” and “twin” are interchangeable terms for a mattress measuring 38 inches by 74 inches, give or take an inch of leeway. Originally this was not the case, as a single bed would refer to just that, one bed with the dimensions of a twin size mattress. Meanwhile, the term twin bed was used to refer to one of two beds, such as a pair of small beds in a children’s room.

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“Single” was once the more popular term, but it has fallen relatively out of favor. Nowadays, you’re more likely to see twin mattress used as the term, even when speaking of only one mattress and not half of a pair.

Best Amerisleep Twin Size Mattresses

Quick Guide: A 30-Second Summary

Best Twin Size Mattress Overall Amerisleep AS3

Our Amerisleep AS3 model is our top recommendation for anyone seeking a compact twin size mattress. The medium feel suits almost any sleep style and it can fit in a small studio apartment or bedroom.

Mattress Highlights
  • Medium feel suits side, back, and combo sleepers
  • Plant-based memory foam stays cool during sleep
  • Five zones of targeted support from HIVE® technology
Recommended For
  • Small bedrooms or single-room studio apartments
  • Guest bedrooms
  • Children's bedrooms and bunk beds

Sleepers who are seeking a twin size mattress often need a bed that packs a lot into a compact design. Whether you’re a young adult living in a smaller space or a parent interested in a mattress for a child, a versatile mattress like the AS3 can be just what you need to sleep well at night.

The first layer inside the AS3 is our exclusive Bio-Pur® foam. We produce this foam by mixing plant-derived oils with traditional memory foam ingredients, creating a foam that is not entirely synthetic. Our plant-based memory foam is more breathable and responsive than traditional memory foam, boosting the bed’s reactive comfort.

The second layer is Affinity foam with HIVE® technology. This layer focuses on targeted support through hexagonal cutouts, placed to establish five distinct zones. In the shoulders and hips, the cutouts are placed to help the mattress mold more to these sensitive areas for pressure relief. Meanwhile, cutouts in the head, back, and feet areas establish responsive support.

The base is Bio-Core® foam. The structure of Bio-Core® foam promotes stability, decreasing the chances of sagging or soft spots from developing. Thanks to Bio-Core® foam, you can expect the AS3 to provide years of comfortable support.

The AS3 is backed by a 100-night sleep trial and a 20-year warranty, as are all Amerisleep mattresses.

Save $450 on the Amerisleep AS3 with our discount code
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When Is a Twin Mattress Right for Me?

Parents often choose a twin size mattress for a child that’s leaving their crib mattress behind. Many mattresses last around eight years. That said, many of the best mattresses can provide comfort and support for over a decade. Parents who are smart shoppers should be able to find a well-made mattress to last their child beyond their final growth spurt.

If parents choose to have two young children share a room, they may place a pair of twin mattresses side by side. Alternatively, they may stack them in a bunk bed if their kids are sharing a smaller room. Just make sure you choose a mattress thickness appropriate for bunk beds, not too tall for any guard rails.

While twin beds are some of the best mattresses for kids, single adults can also use them. After all, a twin mattress is inexpensive, as are its corresponding accessories. So it’s the perfect size for budget shoppers.

Similarly, a twin size mattress is a good choice for anyone who needs to make the most of a small bedroom or studio apartment. Young adults with cramped living quarters may even want to maximize their room’s potential with a lofted bed frame. This raised bed frame gives them room to place a dresser or desk underneath their bunk.

Even adults who don’t have the space and funds for a larger mattress may want to keep a twin mattress tucked away in a guest room for visitors.

Prices of All Amerisleep Twin Mattresses

Amerisleep AS1$649
Amerisleep AS2$849
Amerisleep AS3$1049
Amerisleep AS3 Hybrid$1249
Amerisleep AS4$1049
Amerisleep AS5$1649
Amerisleep AS5 Hybrid$1949
Amerisleep Organica$1049

Other Mattress Sizes

Whether you call it a single or twin mattress, this small bed isn’t the only standard mattress size to consider. For many sleepers, a twin mattress is wholly unsuitable for their needs. Instead, they require a larger mattress to sleep comfortably.

To save you the trouble of measuring your mattress, we list the dimensions and potential uses of other sizes below.

Twin XL

Twin XL size mattresses are a longer version of the standard twin mattress, measuring 34 inches by 80 inches. The extra length helps a twin XL bed accommodate taller sleepers, particularly those over 6 feet.

A twin XL mattress’s dimensions allow it to fit in the same space that a twin bed would while providing a more versatile sleep surface. This is why many dorm rooms and smaller guest bedrooms contain a twin XL bed instead of a regular twin. Parents seeking a mattress for older children may prefer a twin XL size bed instead.


Full size mattresses are wider than a regular twin mattress, making them perfect for solo sleepers who move around as they sleep. Measuring 54 inches wide and 75 inches long, they’re big enough to feel roomy and compact enough to fit in most bedrooms.

Much like single and twin, full mattresses can confuse shoppers with the fact they’re sometimes referred to as double beds. This nickname can be misleading as it suggests full beds can accommodate two people. However, we cannot recommend full size beds for couples.

Two people who share a full mattress will have a sleeping space roughly equivalent to a crib mattress, leaving them with little room to toss and turn. When it comes to mattresses for couples, we always suggest mattresses queen size and larger.


If you’re a solo sleeper considering a twin size mattress, you may not be in the market for a bed as expansive as a queen size mattress. Still, if you have an average size bedroom and are interested in a mattress that can accommodate a partner, a queen mattress is an excellent choice.

Queen beds are the most popular mattress size because they can suit single sleepers and couples, are affordable mattresses on most budgets, and can squeeze into the typical bedroom.


Some couples prefer more personal space than what a queen mattress can provide, while a few single sleepers want a mattress that’s luxuriously large. A king size mattress can meet the interests of both groups with its spacious dimensions. The traditional king bed measures 80 inches long and 76 inches long.

The main drawback of a king size mattress is that you need a relatively large bedroom to accommodate it. Anything smaller than a traditional master bedroom can leave a sleeper feeling confined on their king mattress. Budget shoppers may also struggle to find a king bed within their means.

California King

A California king size mattress is the lengthiest standard size, measuring 84 inches long. It’s also 4 inches narrower than a traditional king, although 72 inches of width is typically enough for two people to share. We recommend California king beds for anyone who’s over 6 ½ feet tall.

How Do I Pick the Right Size for Me?

Choosing a bed size is relatively easy once you understand it mostly comes down to considering four different things:

Room Space

Twin and twin XL mattresses can slip into small rooms, while full and queen mattresses often benefit from being placed in a room that’s at least 10 feet by 10 feet. A king size mattress, regardless of whether it’s a standard or California king mattress, fits best in rooms at least 12 feet by 12 feet.

Budget Constraints

Naturally, a larger mattress costs more than a smaller size. People who may have the room for a queen and would enjoy the space may instead choose a full or twin size bed simply because it costs less.

Number of Sleepers in the Bed

We only recommend queen or king size beds for sleepers who want to share with a partner.

Personal Preferences

Some people prefer more sleeping space than others. This may mean choosing a full instead of twin bed if they’re sleeping alone. People who intend to share may choose a king instead of a queen bed.

Frequently Asked Questions

What is the difference between a twin bed and a double?

Doubled beds are another name for full size mattresses, which measure 16 inches wider than a twin mattress. The two sizes are often the same length, measuring 75 inches long. However, a twin mattress may be an inch shorter than a full bed.

While a double bed is broader than a twin mattress, we can’t recommend it for people who want to share. Double mattresses are roughly as wide as two crib mattresses pushed together. These mattress dimensions don’t give two sleepers sufficient space to move and change position.

Are two twins a king?

No, two twin beds together do not equal the dimensions of a king size mattress. There is no mattress size that is the equivalent of two twin mattresses placed side by side. Shoppers may become confused because two twin XL size mattresses pushed together equal a king size mattress, known as a split king bed.

Is a twin bed good for adults?

Yes, a twin bed is perfectly suitable for an adult sleeper who’s under 6 feet tall. We would recommend a twin mattress for adults living in a smaller bedroom or studio apartment or for shoppers looking for a new mattress on a tight budget.

Adults taller than 6 feet who are interested in an inexpensive, space-saving mattress should find a twin XL mattress suits their needs well enough. The added length lets them stretch out their legs without fear of their feet hanging off the edge.

Is there a bed smaller than a single?

Yes, there are beds smaller than a single or twin size mattress, though most aren’t considered standard sizes. The exception is a crib mattress, which is typically around 52 inches long and 28 inches wide.

Other sizes smaller than a single or twin mattress include toddler beds, which are often around the same size as a crib mattress but have a softer feel. Plus, the small single size, which is narrower than a standard twin bed.

What size bed should I get for my height?

If you’re an adult under 6 feet tall, you should be able to fit comfortably on any size mattress. You can choose a twin or twin XL mattress if you’re working with a smaller bedroom or budget. Conversely, a full mattress is excellent if you want to stretch out. Do you want to provide space for a partner? Then you may want to consider a queen size or larger.

If you’re over 6 feet tall, you have fewer mattress options to consider. A twin XL mattress is fantastic if you need a budget mattress. Meanwhile, a queen, king, or California king size mattress gives you sprawling space.

Is a Twin Size Mattress Right For Me?

For many children and young adults, a twin or single mattress that suits their needs perfectly. Others may need the extra space of a twin XL or full mattress. Considering not just works for you now but what you will want to sleep on in the future (i.e., will you still want a twin mattress two, three, or five years from now?) can help you pick the right mattress size.

About the author

Mitchell Tollsen is a graduate student and a freelance writer who’s contributed to the Early Bird blog for three years. Mitchell’s always been fascinated by the science of sleep and the restorative processes our bodies undergo when at rest. The self-titled “Sleep Expert” is always looking for ways to improve his shut-eye, and throughout the years has implemented numerous lifestyle changes and tried dozens of sleep-promoting gadgets to determine the best ways to truly get better rest.

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