Scale of the American Library Association
| Size Name | Symbol | Outside Height* | Appx Size in Inches* |
|---|---|---|---|
| folio | F | over 30 cm | 12 x 19 |
| quarto | Q | 25-30 cm | 9½ x 12 |
| octavo | O | 20-25 cm | 6 x 9 |
| imperial octavo | O | - | 8¼ x 11½ |
| super octavo | O | - | 7 x 11 |
| royal octavo | O | - | 6½ x 10 |
| medium octavo | O | - | 6 1/8 x 9¼ |
| crown octavo | O | - | 5 3/8 x 8 |
| duodecimo | D | 17.5-20 cm | 5 x 7 3/8 |
| duodecimo (large) | D | 17.5-20 cm | 5½ x 7½ |
| sextodecimo | S | 15-17.5 cm | 4 x 6¾ |
| octodecimo | T | 12.5-15 cm | 4 x 6½ |
| trigesimo-segundo | Tt | 10-12.5 cm | 3½ x 5½ |
| quadrasegisimo-octavo | Fe | 7.5-10 cm | 2½ x 4 |
| sexagesimo-quarto | Sf | less than 7.5 cm | 2 x 3 |
*Approximate Size refers to the front cover's rectangular dimensions
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 6½ X 9¼ 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)
British book sizes
| Size Name | Octavo Size | Quarto Size |
|---|---|---|
| pott | 6¼ by 4 | 8 by 6¼ |
| foolscap | 6¾ by 4¼ | 8¼ by 6¾ |
| crown | 7½ by 5 | 1O by 7½ |
| large crown | 8 by 5¼ | 10½ by 8 |
| large post | 8¼ by 5¼ | 10¼ by 8¼ |
| demy | 8¾ by 5 5/8 | 11¼ by 8¾ |
| post | 8 by 5 | 10 by 8 |
| small demy | 8½ by 5 5/8 | 11¼ by 8½ |
| medium | 9 by 5¾ | 11½ by 9 |
| small royal | 9¼ by 6 1/8 | 12¼ by 9¼ |
| royal | 10 by 6¼ | 12½ by 10 |
| super royal | 10¼ by 6¾ | 13½ by 10¼ |
| imperial | 11 by 7½ | 15 by 11 |













