Twin Size Mattress Dimensions: How Big Is a Twin Size Bed?
By Andrew Russell, Wellness Writer 
Not counting a crib mattress, a twin mattress is the smallest standard size available. It’s an affordable mattress for sleepers who don’t need much space or are trying to make the most of a studio apartment or small bedroom.
A twin size mattress is usually 38 inches wide and 75 inches long, for a total surface area of 2,850 square inches. The dimensions can vary slightly by companies, with some selling twin size mattresses that are 39 inches wide instead. We recommend a twin size mattress for any room that’s at least 7 feet by 10 feet.
Twin and Twin XL Mattresses
There’s only one variation of the standard twin mattress— a twin XL size mattress. It is as wide as a twin bed, but with 5 extra inches of length for a total of 80 inches. That makes the surface area 3,040 square inches.
A twin XL mattress is an excellent choice for a child’s first bed that should last well into their teen years. The extra 5 inches can accommodate most growth spurts, and a young adult will likely be able to bring their twin XL bedding with them to college. Most college dorms contain twin XL size bed frames and mattresses.
A twin mattress may be the better option for those who are shopping on a tight budget or are trying to make the most of a small space.
Twins, Singles, and Doubles
When shopping for a twin size bed, you may be confused by references to single size mattresses or double size mattresses. A single mattress shares the same dimensions as a twin size mattress.
The difference between the two is that a single mattress is just that, a single mattress. A twin mattress is supposed to refer to one of two mattresses, such as a matched pair of twin beds for a guest room. Companies and customers often use the two terms interchangeably, so you might see an unpaired mattress referred to as a twin bed.
You may also find references to a small single mattress, which measures 30 inches by 75 inches. A small single mattress is often used for a toddler bed, transitioning the child from a crib to a larger mattress.
A double mattress is not the same thing as a twin size mattress. Instead, a double bed is another name for a full size mattress, which is 16 inches wider than a standard twin. Double beds were once a popular option for couples, but now, they are usually only recommended for single sleepers.
Who Should Sleep on a Twin Mattress?
A twin or a twin XL mattress is a natural fit in any child’s bedroom. Whether it’s just one mattress or two for a bunk bed, growing children will be able to rest comfortably on a twin mattress for many years. If you invest in a high-quality twin mattress, the bed can last a child until they’re ready to leave home and buy a new mattress.
Twin mattresses are also a good choice for adult sleepers who have limited space in their home. A twin mattress fits in most smaller rooms, just don’t forget to factor in 2 to 5 more inches for a twin’s bed frame dimensions. Plus, a twin bed is more lightweight than larger sizes, making it easier to take your mattress with you if you move.
A twin bed is also an excellent mattress for a guest room. While small, it’s able to provide most single sleepers with all they need for a good night’s rest.
You don’t even have to use a twin mattress for sleeping. If you want to set up a daybed (a mattress made up like a sofa for daytime relaxation) a twin mattress is the perfect size.
Other Bed Sizes
A twin size mattress isn’t the right bed for everyone, particularly if you’re looking for a bed large enough to share. You have four other mattress sizes you can consider as you shop for your perfect bed.
Full Mattress
Dimensions: 54 inches by 75 inches
A full size mattress is an excellent choice for a single adult who wants room to sprawl but is short on living space. A full bed feels more luxurious than a twin but doesn’t take up as much space as a king or queen. If a college dormitory doesn’t have a twin XL size mattress, it’s likely to have a full size bed instead to accommodate most sleepers.
Taller sleepers might want to consider a full XL size mattress, which is 5 inches longer than a standard full size bed. Be aware that it might take some hunting to find a full XL mattress since it’s not a standard size. Your best chance of finding one is by looking online.
Queen Mattress
Dimensions: 60 inches by 80 inches
A queen size mattress is the most popular mattress size because it suits a wide range of sleepers and fits in many bedrooms. Are you shopping for a good mattress for couples, or do you just want a mattress you can sprawl across before you drift off to sleep? In either scenario, a queen mattress is an excellent choice.
You also have more to consider than just the standard queen size bed. If you need a mattress with a little extra width, an Olympic queen offers six more inches of sleeping space. And a California queen is 4 inches longer than a regular queen, giving sleepers over 6 feet tall some needed legroom.
Both of these variations are nonstandard, so you may have to custom order one if you’re interested.
King Mattress
Dimensions: 76 inches by 80 inches
A king size mattress is an excellent way to complete any master bedroom. It’s the largest standard size mattress available and provides two people with about the same amount of sleeping space that they would each have on a twin XL mattress.
There are many variations of a king size mattress. Aside from a California king, which we cover below, there is also the split king and nonstandard plus-sized options such as the Wyoming king, the Texas king, and the Alaska king.
A split king mattress has the same dimensions as a standard king, but it’s cut into two mattresses to let couples customize their side of the bed. However, a split king is typically more expensive than a standard king, which is already a costly mattress size. Read our king vs. split king article if you’re interested in learning more about the pros and cons of a split king.
California King Mattress
Dimensions: 72 inches by 84 inches
A California king size mattress is 4 inches longer than a standard king. In exchange, the bed is also 4 inches narrower than a normal king. A California king mattress is a good choice for a tall sleeper who wants the space to lie down without having to curl up or let their feet dangle over the edge.
A king and a California king mattress usually cost about the same, but California king size bedding and bed frames are often more expensive than the equivalent accessories for a standard king. Be sure to check out our king and California king comparison guide if you’re undecided between the two.
Did We Help?
A twin mattress isn’t the best mattress for everyone, but it is an excellent option if you’re shopping for a smaller bedroom or studio apartment. Most single sleepers can rest comfortably on a twin mattress.
Even if you’re interested in a bigger mattress for your bedroom, a twin mattress can let you unwind during daylight hours as a daybed mattress.
This article is for informational purposes and should not replace advice from your doctor or other medical professional.
Andrew Russell, Wellness Writer 
Andrew Russell is a part-time writer and full-time sleep enthusiast. At Zoma, Andrew lends his sleep expertise and writes many of our “better sleep” guides. Outside of Zoma, Andrew puts his advice to the test, always trying new ways to get deeper, more restorative sleep. We appreciate Andrew because he doesn’t give advice that he doesn’t follow himself, so you can feel confident his solutions for better sleep really do the trick. Andrew's work has been featured on Ladders, Bright Side, and several other publications.
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