Book Sizes and Formats


Glossary - Book Sizes and Formats
: The Origins & Meanings of 8vo., 4to. and Such.; The terms used in descriptive bibliography to designate the Format (shapes) of books often cause more confusion than clarity. Terms such as folio, quarto (4to), octavo (8vo), etc. were coined based on the printing practices developed in the pre-1800 hand-press period, and continued to be used (albeit often inexactly) after the introduction of machine-printing. The precise use of these terms apply only to books printed and assembled in a certain manner, and printed on handmade or Laid Paper with chain lines.; Such books had sections of their future pages ( Gatherings) printed on both sides of large, single sheets of paper. A book's height & format are determine by how many times these sheets are folded since the final folding results in the size and shape of what will become a section of Leaves in the book. Folding a sheet parallel to its short side produces 2 leaves (or 4 pages), folding again results in 4 leaves (hence, quarto), thrice gives 8 leaves (hence, octavo), and so on. If the sheet is folded parallel to its long side into thirds, then folded twice the other way, these 12 folds create a 24 leaves in a useful format called a duodecimo (12mo). Folding a 12mo produces a 24mo, etc. As shown in Figure 2, each folding produces shapes which either tend toward the squarish or a tall, more narrow format.; If all books printed in this manner had been printed on the same size sheets, the height of a book would be determined automatically by its format. Unfortunately, even early printers used sheets which varied widely in size making the height of a book still dependent on the original size of the sheets even if its has the proper shape for the number of folds made in the sheets. It is here that chain lines become important. Because they are always parallel to the shorter side of the sheet, a folio format will always have gatherings of 2 leaves with vertical chain lines while those of a quarto will be 4 leaves with horizontal lines. With some exceptions beyond the scope of this glossary, the technically precise assignment of a format to a book mass produced after the 18th century is not really possible. Despite this, booksellers have continued the practice of describing a book's size in terms of formats based largely on the shapes of sheets most commonly used in bookmaking (roughly in a 3 to 4 ratio), and, when possible, the number of leaves in a book's gatherings. Why we booksellers continue this practice remains a mystery even to us.

: Understanding Book Formats Given in this Catalog.; The usual format abbreviations in Figure 2 above are used, but modified (when necessary) by a descriptive term to aid visualizing the height and shape of a book.; Each Line Inside the Sheet is a Fold.
Arrows Indicate the Usual Orientation of the Format.
A book bound along one of its shorter edges is called Oblong.; STEP ONE: Match the format abbreviation given in the description for the book with its shape in Figure 3 above. This gives the shape of the book.; STEP TWO: If there is no additional descriptive term given with the format abbreviation, the height of the book falls within the range given in Figure 2 above.; STEP THREE: If there is an additional term, use Figure 4 below to determine the modification.

Abbreviation	Format Name	Description
Folio	Folio	A book up to 15" tall
4to	Quarto	A book up to 12" tall
sm4to	Small Quarto	A book up to 10" tall
8vo	Octavo	A book up to 9 3/4" tall
sm8vo	Small Octavo	A book up to 8" tall
12mo	Duodecimo	A book up to 7 3/4" tall
16mo	Sextodecimo	A book up to 6 3/4" tall
24mo	Vigesimo-quarto	A book up to 5 3/4" tall
32mo	Trigesimo-segundo	A book up to 5" tall.
48mo	Quadragesimo-octavo	A book up to 4" tall
64mo	Sexagesimo-quarto	A book up to 3" tall
Seldom Seen Large Animals	Elephant Folio	A book up to 23" tall
	Atlas Folio	A book up to 25" tall
	Double Elephant Folio	A book up to 50" tall

FORMATS	TALL	OBLONG	SMALL	NARROW	SQUARE	EXTRA
TALL FORMATS Folio, 8vo., 24mo., 32mo.	Same shape, but proportionally a little taller	Same shape and dimensions, but bound along one of the shorter edges	Same shape, but proportionally a little shorter	Same height, but a little narrower	Not Applicable	Same shape, but proportionally more than just a little taller, shorter, etc.
SQUARISH FORMATS 4to., 12mo., 16mo., 48mo., 64mo.	Same shape, but proportionally a little taller	Same shape and dimensions, but bound along one of the shorter edges	Same shape, but proportionally a little shorter	Not Applicable	Just enough wider to make a square format.	Same shape, but proportionally more than just a little taller, shorter, etc.

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