A twin extra long bed, or twin XL bed, is 39 inches wide by 80 inches long. It is five inches longer than a standard twin bed, which measures 39 inches wide by 75 inches long.
Twin XL beds are commonly used in dorm rooms. While a standard twin bed easily fits into small spaces, it is too short for many adults. A twin XL is still compact enough for smaller bedrooms, but the extra length accommodates taller teens and adults. Extra long twins also provide flexibility for guest bedrooms because they are long enough to accommodate both children and adults. Two can be used separately or pushed together to form one king size bed. A twin XL mattress requires extra long bedding, which is not as readily available as standard twin bedding and may not be offered in as many patterns or colors.