5x10, about the size of a large walk-in closet, 10x10, about the size of a child's bedroom (as of 2015, 10x10's are the most common storage unit size, making up 16% of the distribution in the U.S.),[8] 10x20, about the size of a one-car garage, 15x20, about the size of a large master bedroom, and 20x20, about the size of a two-car garage.