Both full beds and twin beds are 75 inches (191 cm) long. They differ when it comes to width, however. At 54 inches (137 cm) wide, a full size bed is nearly as wide as a queen size bed. Twin beds are much narrower, measuring a mere 39 inches (99 cm) across.
http://www.diffen.com/difference/Full_Bed_vs_Twin_Bed
Non-Standard Dimensions. Both full and twin beds have extra-long, or XL, versions, which add an extra five inches (13 cm) to the bed's length. At 80 inches (203 cm), this makes these versions of full and twin size beds as long as king and queen size beds.
http://www.diffen.com/difference/Full_Bed_vs_Twin_Bed
Twin beds are used for bunk beds too. Overall dimensions: 39 wide x 75 long. Width per person: 39. Pros: Because of its small size it will fit easily into smaller bedrooms. Twin sheets are the least costly of all sheet sizes and are available in lots of patterns. It's easy to make a twin bed. Cons: A standard size is too short for many adults.
https://www.thespruce.com/is-a-twin-bed-right-for-you-1976223
A twin XL model measures at 39 inches by 80 inches, which is about 5 inches longer than a standard twin mattress. This size bed is perfect for one tall sleeper, and having two of them in a larger guest room is always a safe option.
http://www.sears.com/articles/home/mattresses-accessories/standard-mattress-dimensions.html
Queen size beds are 21 wider and 5 longer than a Twin bed and 6 wider and 5 longer than a Double size bed. Though this extra width and length can make all the difference in getting a good night's sleep, each adult still has 9 less of width than if they each slept in a twin bed.
https://www.thespruce.com/is-a-twin-bed-right-for-you-1976223
Twin XL. The twin’s slightly longer cousin, the twin XL mattress is the most popular size for college dorm rooms. It’s five inches longer than a twin, making it 39 inches wide and 80 inches long. In addition to students, a twin XL mattress is a good solution for taller teenagers and individual adults with limited space.
https://casper.com/mattress-size-comparison-guide
A twin model is 39 inches by 75 inches and typically works best in a smaller bedroom, on a daybed or with a bunk bed set. While it's possible to have two sleepers on a twin size mattress, it might be too snug. Benefits of a Twin Size Mattress. A twin size mattress fits in small bedrooms where space might be limited.
http://www.sears.com/articles/home/mattresses-accessories/standard-mattress-dimensions.html
The most popular mattress size around, the queen mattress fits best in a master bedroom that’s at least 10 x 10 square feet. At 60 inches wide and 80 inches long, the queen offers plenty of space for couples or individuals who like having extra room to move around in bed.
https://casper.com/mattress-size-comparison-guide
Twin XL mattresses are approximately 38 x 80. Full size mattresses are approximately 53” x 75”. Queen size mattresses are the most popular standard size available and are approximately 60 x 80. King size mattresses are the largest standard size available and are approximately 76 x 80.
https://www.originalmattress.com/mattress-and-box-spring-sizes
Length and width dimensions for mattresses and box springs have a tolerance range of ± 1” for standard sizes (Twin, Full, Queen & King) and ± 1 ½” for custom sizes (Twin XL, Full XL, California King, etc.). Twin size mattresses are the smallest standard size available and are approximately 38 x 75.
https://www.originalmattress.com/mattress-and-box-spring-sizes
what are the dimensions of twin xl
The dimensions of twin XL is 39 inches by 80 inches. The dimensions of twin xl is 39 inches by 80 inches. The dimensions of twin XL is 39 inches by 80 inches, which is about 5 inches longer than a standard twin mattress. The dimensions of twin extra large is 39 inches by 80 inches, which is about 5 inches longer than a standard twin mattress. The dimensions of twin XL is  39 inches by 80 inches.  