If a sheet 19 inches (480 mm) by 25 inches (640 mm) is used to print a quarto, the resulting untrimmed pages, will be approximately half as large in each dimension: width 9+1⁄2 inches (240 mm) and height 12+1⁄2 inches (320 mm). An octavo page, oriented a quarter turn from the full sheet, would have height ½ × 19 = 9+1⁄2 inches (240 mm) and width ¼ × 25 = 6+1⁄4 inches (160 mm). The sizes of books of the same format will differ in proportion to the full sheets used to print them.