Glossary Term Image

Book formats

The traditional terms in use for describing book formats are derived from early printing methodology and the size of early handmade sheets of paper. When two leaves (four pages when printed on both sides) were printed on a sheet so that it could be folded once, collated with other folded sheets and bound, the format of the volume was a "folio". When four leaves (eight pages) were printed on the same size sheet, which would later be folded twice, the format of the resultant volume was a "quarto" (four leaves). The term "octavo" relates to the sheet having eight leaves printed on it.

Today some booksellers are providing the height of a book in inches or centimeters rather than using these early terms which do not relate directly to the sheet size or process used for printing today. The following is offered as a guide to convert book formats to approximate book sizes:

  • Folio: more than 13 inches tall;
  • Quarto (4to): approx. 10 to 13 inches tall, average 12 inches;
  • Octavo (8vo): approx. 8 to 10 inches tall, average 9 inches;
  • Duodecimo (12mo): approx. 7 to 8 inches tall, average 7.5 inches;
  • Sextodecimo (16mo): approx. 6 to 7 inches tall, average 6.5 inches. There are smaller and larger books, i.e. many miniatures are 64mo, and most hard bound books are either octavo or duodecimo in size.