average length and width of a bookcase
For ease of shelf access, bookcases are generally no higher than 84 inches. Small bookcases are usually 30 to 42 inches high. The highest shelf in a bookcase should be as. high as an average-sized person can comfortably reach about 72 to 78 inches.. Shelf depth is determined by the size of the items to be stored, generally within the range of 6 to 24 inches. Shelf depth for a general purpose bookshelf is usually 10 to 12 inches.