Updated July 3, 2026
With so many mattress sizes to choose from, it’s no easy feat to determine which is right for your needs. If you’re a single sleeper looking for a space-efficient mattress, you’ve likely come across the terms “single” and “twin” bed. But what’s the difference between a single vs. twin?
In short, single and twin are the same thing. Both mattresses are 38 inches by 75 inches and are designed for single sleepers and small spaces.
Want to learn more about single and twin beds? Keep reading to learn the history of the two bunk bed-sized mattresses.
Our innovative twin size mattresses are the perfect combination of support, cooling, and comfort. They’re squeezed into a tiny box, which is magically delivered to your doorstep within a few days.
Single vs. Twin Bed: What’s the Difference?
The terms “twin” and “single” both refer to the same bed size. Both a twin and single bed are 38 inches wide and 75 inches long. While the terms are often used interchangeably, twin has become the more popular way to refer to this specific bed size.
Here are some fast facts explaining how the twin bed got its name:
- After the Civil War, mattress manufacturers predominantly made two bed sizes: single (twin) and double (full).
- The term originated from hotels that used to place two single beds together to make a double.
- While you may think that the name “double” suggests that a double mattress is twice as wide as a single — and hey, who could blame you? — double mattresses are actually only 16 inches wider than a single.
- Eventually, people switched to the arguably more logical terms “twin” and “full” — with twin referring to a single mattress and full referring to a double.
Although the terms “single” and “twin” are somewhat interchangeable, twin is more common nowadays.
Single and Twin Bed Dimensions
Here are some quick figures on single vs. twin bed dimensions:
- Single mattress width: 35”
- Single mattress length: 75”
- Single mattress size: 38” x 75” or 2,850 square inches
Did you know that some twin beds can be put together to make a bed that’s almost the exact size of a king? However, to make a true king bed, you’d need two twin XL mattresses, which measure 38 inches by 80 inches. Check out some more fun size comparisons below:
How To Choose Your Mattress Size
Whether you’re looking for a space-saving twin or more room to sprawl, check out these important factors to consider when choosing your mattress size.
Factor #1: Your Height
Since twin mattresses are 75 inches long, taller sleepers may prefer the extra 5 inches of a twin XL mattress. Here’s a basic breakdown of the various mattress heights:
- Twin mattress height: 6’3”, suitable for sleepers with a height of under 6 feet
- Twin XL mattress height: 6’8”, suitable for most sleeper heights
When you factor in the additional length added by your pillows (a standard pillow is 18 inches by 26 inches), taller sleepers may find their feet hanging off the end of a regular twin mattress.
Factor #2: Cost
Twin and twin XL mattresses are typically the most affordable sizes on the market, making them a smart choice if budget is top of mind. Because they use less material than larger sizes, you'll generally pay less across the board, whether you're shopping for an entry-level foam mattress or a premium hybrid. That savings can add up, especially if you're furnishing a guest room, a kid's room, or a dorm.
Browse our full lineup of twin size mattresses to find the right fit for your budget.
Factor #3: Room Size
If you’re a single sleeper with limited bedroom real estate, a twin bed may be the wiser choice. Generally, twin beds are recommended for rooms as small as 7 by 9 feet. If you have other furniture such as a dresser, desk, or bedside table, a twin bed may be a good choice.
However, you should remember that everything is relative. Some people with small bedrooms will opt for a larger full size bed that touches three walls — this is particularly common in large cities with small apartment sizes. As long as your mattress fits within your room dimensions, we say do what’s coziest for you!
Factor #4: Thickness
Most mattresses range in thickness from 9 to 12 inches. We’ve found the bed height sweet spot to be 11 inches for that perfect balance of support and plushness.
When choosing your preferred mattress thickness, it’s important to know that thicker isn’t always better. If you choose a too-thick mattress and add a mattress topper, you may struggle to find sheets that fit your custom bed dimensions. Luckily, Casper sheets are designed with a depth of 18 inches, making them compatible with most bed heights and mattress toppers.
Factor #5: Composition
One of the most important factors in choosing a mattress is composition, which is the materials the mattress is made of.
Do you prefer the support of memory foam or the responsiveness of a hybrid? For those who prefer a softer feel, you may want to opt for a memory foam mattress, while those who enjoy firm responsiveness may favor a traditional innerspring mattress.
Check out our guide to the different types of mattresses for a full breakdown or take a look at the image below for a quick view.
Factor #6: Compatibility
When choosing your mattress, you’ll also want to think about the accessories that go along with it. Are you getting a custom headboard? What about a body pillow?
Many headboards are designed for larger bed sizes, like queen and king beds. If you love the look of a headboard but want a twin bed, check out our bed frames to find your perfect fit.
Who Should Buy a Single or Twin Bed?
A single or twin bed can be a smart choice for a variety of sleepers, especially when space, budget, and sleeping needs are top considerations.
- Children's rooms: Twin beds are ideal for children’s rooms because they provide plenty of sleeping space while leaving more room for toys, desks, and other furniture. Learn more about how to choose a mattress for a child in our blog.
- Solo sleepers: Adults who sleep alone and prefer a compact sleep setup may find a twin bed offers enough room to sleep comfortably without taking up unnecessary floor space.
- Guest rooms: Twin beds are a practical choice for guest rooms, providing a comfortable place for visitors to sleep while maximizing usable bedroom space.
- Bunk beds: Twin mattresses are commonly used in bunk beds, making them a great option for shared children's rooms, vacation homes, or households accommodating multiple sleepers.
- Taller sleepers: Those who need extra legroom may want to consider a twin XL mattress, which offers the same width as a standard twin but measures 80 inches long instead of 75 inches.
Find Single/Twin Mattresses at Casper
Finding your perfect mattress match is not an easy task (say that five times fast!). You’ll want to consider factors such as room size, your height, and the amount of money you want to spend when browsing twin mattresses.
Want to compare other popular mattress sizes? Check out our mattress size comparisons below so you can make an informed decision about what bed size is right for you:
Ready for a great night’s sleep? Turn to our unique mattress lineup to find the perfect bed for your needs. And if you don’t, just return it within 100 days and try again — on the house.
FAQs
What is the difference between twin and full beds?
The primary difference between twin vs. full beds is width. A standard twin mattress measures 38 inches wide by 75 inches long, while a full-size mattress measures approximately 54 inches wide by 75 inches long. Both have the same length, but a full bed provides significantly more sleeping space, making it a better option for adults who want extra room to stretch out comfortably.
Is there a bed smaller than a twin size bed?
Yes. While twin beds are the smallest standard mattress size commonly used by children and some adults, crib mattresses are smaller and designed specifically for infants and toddlers. Some specialty mattress sizes also exist, but for most households, a twin mattress is considered the smallest practical option for a single sleeper.
Can two adults sleep on a twin bed?
Technically, two adults on a twin bed is doable, but it likely won't be comfortable for long. A standard twin mattress provides limited sleeping space for one person and very little room for two. Most couples will sleep more comfortably on a full-size mattress, queen, or king bed that offers additional width and better freedom of movement.
