Adult standard mattress sizes range from the twin, which is 3.2 feet wide by 6.25 feet long, to the California king, which is 6 feet by 7 feet. Other standard sizes include the 4.4-by-6.25-foot full mattress, the 5-by-6.7-foot queen mattress, and the 6.3-by-6.7-foot king mattress.
Adults should sleep on a full mattress or larger, the Better Sleep Council recommends. Because twin and full mattresses are only 6.25 feet or 75 inches long, taller adults may require a queen or king mattress instead. At 7 feet or 84 inches long, the California king accommodates very tall adults best.
Couples who share a bed should opt for a queen mattress or larger, notes the Better Sleep Council. A queen mattress is also a good choice for a guest room. At 18 inches wider than a queen, a king mattress offers couples the most sleeping room.
Other mattress sizes include the twin XL, the futon, and mattresses sized for small children. The twin XL adds several inches of length and is most commonly seen in college dorm rooms. Mattresses for young children include crib mattress and toddler mattresses. Once a child reaches two years of age or 35 inches in height, the Better Sleep Council recommends switching from a crib to a standard twin or full mattress for greater freedom of movement.