Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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book sizes

The dimensions of books, as measured, in inches, centimeters, or millimeters, from head to tail and from spine to fore edges of the cover. The descriptions given to book sizes are based on a still currently used system that involves using the size of a leaf as a fraction of the folded sheet on which it was printed. With reference to the printing of books, an even number of leaves always results when a sheet is folded, i.e., 2, 4, 8, 16, etc., resulting in printed pages on each side of the leaf, i.e., 4, 8, 16, 32, etc. Except for the largest size, the FOLIO (1) , the name of the size indicates the fractional part of the sheet one leaf occupies, e.g., quarto (2 folds, 4 leaves, 8 pages), 1/4 Of the sheet; octavo (3 folds, 8 leaves, 16 pages), 1/8 of the sheet, etc. In this system, since books are printed from different sizes of sheets (See: BOOK BASIS ), the fractional designation by itself cannot denote an exact size; therefore it is a common practice to give the name of the sheet before the fractional name, e.g., royal octavo, which is an octavo 1/8 the size of a sheet 20 X 25 inches or, excluding the SQUARES , a book 10 x 6 1/4 inches (before trimming). Paper is cut to so many sizes, however, that the terms crown, royal, post, etc., unless qualified, are practically meaningless. See: SIZES OF PAPER . Untrimmed sizes for three commonly used sheet sizes are given below. The customary trim of 1/8 inch at head and tail will reduce the height of the text block by 1/4 inch; however, the size of the bound book. assuming 1/8 inch squares will make the height of the book the same as the sizes given. It should be mentioned that not all sheet sizes given are folded to produce books of the very small size indicated. All folds, following the first, are right-angle folds.

The common book-trade designation of sizes was originally related to a sheet of handmade paper measuring 19 X 25 inches, which was the common size of the papermaking mold. When folded to 8 leaves, or 16 pages, and trimmed, each was 6 1/2 X 9 1/4 inches, approximately, and was the standard dimension of an 8vo. When folded to make 16 leaves, or 32 pages, it was a 16 mo. With the present great variety of paper sizes, all dimensions are by necessity only approximate. (52 , 69 , 140 , 156 , 169 ) 

                             Book sizes
 Size       Name           Times    Leaves      Pages    Size of Untrimmed
(in inches)                Folded  per Sheet  per Sheet     Page (leaf)
25 by 38    folio            1         2          4          25 by 19
25 by 38    quarto           2         4          8          19 by 12 1/2
25 by 38    octavo           3         8         16      12 1/2 by 9 1/2
25 by 38    sixteenmo        4        16         32       9 1/2 by 6 1/4
25 by 38    thirty-twomo     5        32         64       6 1/4 by 4 3/4
25 by 38    sixty-fourmo     6        64         18       4 3/4 by 3 1/8
20 by 25    folio                      2          4          20 by 12 1/2
20 by 25    quarto           2         4          8      12 1/2 by 10
20 by 25    Octavo           3         8         16          10 by 6 1/4
20 by 25    sixteenmo        4        16         32       6 1/4 by 5
20 by 25    thirty-twomo     s        32         64       2 1/2 by 3 1/8
20 by 25    sixty-fourmo     6        64         128      3 1/8 by 2 1/2
18 by 23    folio                      2          4          18 by 11 1/2
18 by 23    quarto           2         4          8      11 1/2 by 9
18 by 23    octavo           3         8         16           9 by 5 3/4
18 by 23    sixteenmo        4        16         32       5 3/4 by 4 1/2
18 by 23    thirty-twomo     5        32         64       4 1/2 by 2 7/8
18 by 23    sixty-fourmo     6        64         128      2 7/8 by 2 1/4

                    Size names and their equivalents
    Old Name      Modern Name        Abbreviation  Symbol
folio                folio           fo or f
quarto               quarto          4to            4°
sexto                sixmo           6to or 6mo     6°
octavo               octavo          8mo or 8vo     8°
duodecimo            twelvemo        12mo          12°
sextodecimo          sixteenmo       16mo          16°
octodecimo           eighteenmo      18mo          18°
vincestmo-quartO     twenty-fourmo   24mo          24°
vegisemo-quarto      twenty-fourmo   24mo          24°
trigesimo-decundo    thirty-twomo    32mo          32°
quadragesimo-octavo  forty-eightmo   48mo          48°
sexagesimo-quarto    sixty-fourmo    64mo          64°

                           British book sizes
Size Name        Octavo Size          Quarto Size
pott            6 1/4 by 4             8 by 6 1/4
foolscap        6 3/4 by 4 1/4     8 1/4 by 6 3/4
crown           7 1/2 by 5            1O by 7 1/2
large crown         8 by 5 1/4    10 1/2 by 8
large post      8 1/4 by 5 1/4    10 1/4 by 8 1/4
demy            8 3/4 by 5 5/8    11 1/4 by 8 3/4
post                8 by 5            10 by 8
small demy      8 1/2 by 5 5/8    11 1/4 by 8 1/2
medium              9 by 5 3/4    11 1/2 by 9
small royal     9 1/4 by 6 1/8    12 1/4 by 9 1/4
royal              10 by 6 1/4    12 1/2 by 10
super royal    10 1/4 by 6 3/4    13 1/2 by 10 1/4
imperial           11 by 7 1/2        15 by 11




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