Full, twin, queen, king and California king are the most common adult size mattresses. Crib and toddler are the most common mattress sizes used for cribs and small children. Mattress manufacturers also make custom-sized mattresses to fit specialty, antique and uniquely sized beds.
Twin mattresses are 39 inches by 75 inches, and full mattresses are 15 inches wider. The queen mattress, at 60 inches by 80 inches, is the most popular adult size. King mattresses are 76 inches by 80 inches and are the largest size typically in stock. California King mattresses are 72 inches by 84 inches, and may need to be specially ordered from the manufacturer or retailer.