Book formats and sizes
The names are based on the original sheet size name that a book is made from. For example a crown sheet folded once will produce a bifolium, that is two leaves of four pages, of approximately 15" x 10" in untrimmed state. The sheets folded again will produce a quarto format of 8 pages, 10" x 7½" and folded yet again will produce a section of 16 pages known as an octavo or 8vo abbreviated of 7½" x 5". These units, known as sections, are then sewn together to produce the text of the book. It should be added that most modern books are produced on reel fed machines but the old sizes are still used, especially in the antiquarian book trade. Many libraries now include a height measurement in centimeters for their holdings and you will notice that we also use this on some of our entries.
Here are the commonest book sizes:
Foolscap 8vo, 17 cm, 6¾" x 4¼"
Crown 8vo, 19 cm, 7½" x 5"
Demy 8vo, 22 cm, 8¾" x 5½"
Medium 8vo, 24 cm, 9½" x 6"
Royal 8vo, 25 cm, 10" x 6¼"
Imperial 8vo, 30 cm, 11¾" x 7½"
Foolscap 4to, 21.5 cm, 8½" x 6¾"
Crown 4to, 25 cm, 10" x 7½"
Demy 4to, 28.5 cm, 11¼" x 8¾"
Medium 4to, 30.5 cm, 12" x 9½"
Royal 4to, 32 cm, 12½" x 10"
Imperial 4to, 38 cm, 15" x 11"
Foolscap folio, 34 cm, 13½" x 8½"
Crown folio, 38 cm, 15" x 10"
Royal folio, 51 cm, 20" x 12½"
Imperial folio, 56 cm, 22" x 15½"
These sizes should not be taken as absolute as trimming, when originally bound, may vary.
A brief note on bindings
A book half bound in leather will have the spine and fore-corners in leather with the rest of the sides in cloth or paper. When the spine is leather only it is known as quarter bound. If the leather extends to around half the board area it is three quarter bound although this is rare. A book with a cloth spine and paper or contrasting cloth sides is said to be half bound in cloth. Binders cloth means that the book has been re-bound at a later stage and is not the original binding. Unfortunately, some book cloths, especially of the nineteenth century, have become very brittle and have not stood the test of time. A readable and very useful manual which we heartily recommend is John Carter’s ABC for Book Collectors. Originally published in 1952 it has gone into a number of editions and is readily available.