Book Sizes

Book sizes refer to the physical dimensions of books. Names of book sizes are based on the old system, still widely used, of considering the size of the page as a fraction of the large sheet of paper on which it was printed. The following table is from Webster's Third New International Dictionary of the English language: Unabridged, p. 252.

Size Name	Times Sheet Folded	Leaves to Sheet	Pages to Sheet	Size of Page in Inches
royal folio	1	2	4	20 x 12 1/2
royal quarto	2	4	8	12 1/2 x 10
royal octavo	3	8	16	10 x 6 1/4
royal sixteenmo	4	16	32	6 1/4 x 5
royal thirty-twomo	5	32	64	5 x 3 1/8
royal sixty-fourmo	6	64	128	3 1/8 x 2 1/2
medium folio	1	2	4	18 x 11 1/2
medium quarto	2	4	8	11 1/2 x 9
medium octavo	3	8	16	9 x 5 3/4
medium sixteenmo	4	16	32	5 3/4 x 4 1/2
medium thirty-twomo	5	32	64	4 1/2 x 2 7/8
medium sixty-fourmo	6	64	128	2 7/8 x 2 1/4
crown folio	1	2	4	15 x 10
crown quarto	2	4	8	10 x 7 1/2
crown octavo	3	8	16	7 1/2 x 5
crown sixteenmo	4	16	32	5 x 3 3/4
crown thirty-twomo	5	32	64	3 3/4 x 2 1/2
crown sixty-fourmo	6	64	128	2 1/2 x 1 7/8

Source: Webster's Third New International Dictionary of the English language: Unabridged.