MattressFirm Logo
Bed Basics
Bed Basics

Twin or Twin XL: How to Buy the Right Size of Bed

A child on a twin mattresses and an adult on a twin XL against a blue star scattered background.
Leo Medrano

The search is on: When you’re on the lookout for a new bed, either for a new space or an existing one, even a little room can mean a lot. That’s where compact beds come in. Read ahead for a walk through all of the key differences between the ever-popular twin bed and the less-common twin XL so you end up with the right choice.

When it comes to twin beds, the standard twin measures “38”x”75” (that’s 2,850 square inches); a twin XL is “38”x”80” (3,040 square inches).

The Importance of Choosing the Right Twin Mattress Size

Both of the narrow 38-inch mattresses are best suited to single sleepers—at 76 inches wide, a king-sized mattress is exactly double the width of a twin. But for taller sleepers who are looking for a narrow sleep option, the twin XL could be ideal. While they appear similar from a distance, the main difference between a twin and a twin XL is in their lengths—twins are 75 inches and twin XL's are slightly longer, at 80 inches (the length of a king bed). This means that a twin XL is generally better for taller people. Beyond that, there is no difference in the 38-inch width measurement, meaning both bed sizes are best suited for single sleepers.

A twin and twin XL mattress side by side with their dimensions next to them. Twin: 75 x 38. Twin XL: 80 x 38
Leo Medrano

How to Decide Which Mattress Is Right for You

It comes down to a small difference in length. Twin beds are perfect for single sleepers, and as Sleep Expert® John McCarty explains, “many parents buy them for their children, for bunk bed setups.” Twin XL beds, on the other hand, are ideal for taller teens and young adults—which is why they've become the go-to bed for college dorms. Still stuck debating which one is best? Read on for a few other factors to keep in mind while shopping.

Cost & Availability

Simply put, a twin mattress is easier to find, and costs less, than a twin XL. The same goes for the accessories, such as sheets and bed frames, that accompany them. So, if you're on a budget or in a hurry, keep in mind that twin XL sheets and accessories can be hard to find, so twins are more widely available.

Bedroom Size

Small space? No problem. Both twin and twin XL mattresses are made to fit most room dimensions. But if you have limited space and you’re not worried about the height of the sleeper, we recommend sticking with a twin size, rather than a twin XL. If you’re not sure if your bedroom can accommodate the additional length of the twin XL, the general recommendation for how to position a bed is to allow for 2 feet of space around the bed.

Height and Sleep Position

If you’re over 6 feet tall, you’ll probably appreciate the additional support of a twin XL mattress—the extra space should prevent your feet from hanging off the edge of the bed. But if you tend to sleep at an angle or with limbs spread out, remember that the twin XL does not offer additional width. A full-sized mattress, though, is 16 inches wider, at 54 inches wide, with the shallower twin-size length of 75 inches.


If you’re shopping for a teenager who’s hit a growth spurt, it can be a good idea to consider a twin XL. The extra length can help prevent taller kids from outgrowing their mattresses too soon, which saves you time and money in the long run. And if they’re going off to college soon, where twin XL is the most common size of mattress, they might appreciate the continuity of having the same-sized bed in both places.

A little research goes a long way, so we hope this guide brought you one step closer to finding the mattress of your dreams. Plus, you can rest easy, knowing that if you ever get stuck, our Sleep Experts® are here to help.

FAQs When Buying a Twin or Twin XL Mattress

What does twin XL stand for?

XL simply refers to the extra length, compared to a regular twin mattress—both mattresses are the same width, so the length is the only difference for this “extra-large” twin.

Will a twin sheet fit a twin XL?

No. Because a twin XL is 5 inches longer than a regular twin, sheets designed to fit a twin will not fit a twin XL, or will pop off the mattress if you do manage to stretch the fabric to fit.

Can I use full sheets on a twin XL?

Since twin XLs are 5 inches longer, and full beds are 15 inches wider, the two mattress sizes need their own sets of sheets.

Will a twin XL mattress fit on a twin-sized frame?

Because a twin XL is 5 inches longer than a twin, it will overhang a regular twin frame, leaving it unsupported, so a twin XL mattress should use a dedicated XL frame.

Is a twin XL big enough to fit two people?

As twin XLs are the same width as a twin bed, they’re not recommended for couples, but only for single sleepers.

What is a split king?

A split king consists of two twin XL mattresses pushed together, with their combined area matching that of a king mattress, or 76-by-80 inches. “Most [twin XLs] are purchased for the split king setup; we don’t see as many twin XL pieces sold as we see traditional twins,” McCarty explains.

How much bigger is a twin XL than a twin?

A twin XL is 80 inches long, which is the same length as a queen or king mattress, while a twin is 75 inches long, which is the same length as a full mattress. Only the California king mattress is longer than a twin XL, at 84 inches.

Are there any essential accessories for twins or twin XLs?

Regardless of size, our Sleep Experts® often recommend sheet sets, pillows and waterproof mattress protectors for all beds.

What is a dorm room college twin?

A twin XL mattress is standard for most college and university dorm rooms and residence halls. Since twin XL beds are made with space-saving in mind, they do not offer more width than a standard twin, with only 38 inches of width.

Sleep Expert Recommended Twin or Twin XL Mattresses