The size of a book is usually measured by comparing the height and width of a leaf, or sometimes the height and width of its cover. Libraries and publishers use a set of terms to describe the general sizes of modern books. These include folio (the largest), quarto (smaller), and octavo (even smaller). These terms originally described how books were made. Printers and experts used them to explain the size of a leaf based on the size of the original sheet of paper. For example, a quarto (from the Latin word quartō, meaning "fourth") was a book made by folding a sheet of paper in half twice. The first fold was at a right angle to the second, creating 4 leaves (or 8 pages). Each leaf was one fourth the size of the original sheet. A leaf is a single piece of paper, while a page is one side of a leaf. Today, because the actual format of many modern books cannot be determined by looking at them, some experts do not use these terms in their descriptions.
Book formats
During the hand press period (up to about 1820), books were made by printing text on both sides of a full sheet of paper. The paper was then folded one or more times to create a group of leaves, called a gathering. A binder would sew these gatherings through their inner edges and attach them to cords in the spine to form the book block. Before adding the covers, the text pages were sometimes trimmed along the unbound edges to smooth the paper and open the folds. If the leaves were not trimmed, readers had to cut the edges with a knife to read the pages.
Books made by printing two pages of text on each side of a sheet, then folding it once to form two leaves (four pages), are called folios. Those made by printing four pages on each side, folding twice to create four leaves (eight pages), are called quartos. Books made by printing eight pages on each side, folding three times to form eight leaves (sixteen pages), are called octavos. The size of the pages depends on the size of the original sheet and how much the leaves were trimmed. If the same paper size is used, folios are the largest, followed by quartos and then octavos. Quartos often have squarer-shaped leaves compared to folios or octavos.
The way books are made is called their format. These terms are often shortened, such as 4to for quarto and 8vo for octavo. An octavo format has pages that are half the size of quarto pages before trimming. Smaller formats include duodecimo (12mo), with twelve leaves per sheet and pages one-third the size of quarto pages, and sextodecimo (16mo), with sixteen leaves per sheet, half the size of octavos and one-quarter the size of quartos. Most books were printed in folio, quarto, octavo, or duodecimo formats.
There are many ways to produce books. For example, folios were often made by inserting multiple printed sheets into one another to create larger gatherings, such as eight leaves (sixteen pages). Bibliographers still call these books folios because the original sheets were folded once to make two leaves, and they describe them as folios in 8s. Similarly, a book printed as an octavo but bound with gatherings of four leaves is called an octavo in 4s.
To determine a book’s format, bibliographers examine the number of leaves in a gathering, their shape and size, and the arrangement of chain lines and watermarks in the paper.
To ensure pages appear in the correct order, printers had to arrange the type in the press carefully. For example, to print two leaves in a folio with pages 1 through 4, the printer would print pages 1 and 4 on one side of the sheet, then pages 2 and 3 on the other side after the ink dried. For a folio in 8s, the printer would print pages 1 and 16 on one side, and pages 2 and 15 on the other side, and so on. This process of arranging pages in the press is called imposition, and different methods are used for each format. Some methods require cutting pages before binding.
Modern book production
As printing and paper technology improved, it became possible to make and print on much larger sheets or rolls of paper. It might not be clear (or even possible to know) by looking at a modern book how the paper was folded to create it. For example, a modern novel may have groups of sixteen leaves, but it could have been printed with sixty-four pages on each side of a very large sheet of paper. Similarly, the actual printing format cannot be determined for books that are perfect bound, where each leaf is completely cut out (not connected to another leaf as in groups) and glued into the spine. Modern books are often called folio, quarto, and octavo based only on their size, not the format used to make them, if that format can even be known. Experts who study books may describe such books by the number of leaves in each group (eight leaves per group forming an octavo), even if the actual number of pages printed on the original sheet is unknown or may choose not to use these terms for modern books at all.
Today, octavo and quarto are the most common book sizes, but many books are also made in larger or smaller sizes. Other terms for book size include elephant folio, which can be up to 580 mm (23 inches) tall, atlas folio, which is 640 mm (25 inches) tall, and double elephant folio, which is 1,300 mm (50 inches) tall.
Paper sizes
During the hand press period, full sheets of printing paper were made in many different sizes. These sizes had many names, such as pot, demy, foolscap, crown, and others. However, these sizes were not standardized, and their actual measurements changed depending on the country and time period.
The size and shape of a book depend on the size of the original full sheet of paper. For example, if a sheet measuring 480 by 640 mm (19 by 25 inches) is used to print a quarto, the untrimmed pages will be about half the size of the sheet in each dimension: 240 mm (9.5 inches) in width and 320 mm (12.5 inches) in height. An octavo page, which is rotated a quarter turn from the full sheet, would measure 240 mm (9.5 inches) in height and 160 mm (6.25 inches) in width. The sizes of books with the same format can vary depending on the size of the full sheets used. For example, a typical octavo book printed in Italy or France during the 16th century is roughly the size of a modern mass market paperback. However, an English octavo book from the 18th century is noticeably larger, similar in size to a modern trade paperback or hardcover novel.
Common formats and sizes
The table below is based on the American Library Association's scale, which uses a standard sheet size of 19-by-25 inches (483 by 635 mm). This sheet is half the size of a 25-by-38-inch (635 by 965 mm) text/book stock sheet. The term "size" refers to the cover dimensions, while trimmed pages are often slightly smaller, usually by about 1/4 inch (5 mm). The words before "octavo" describe traditional names for unfolded paper sheet sizes. Other dimensions may also be used. The US Trade size matches octavo and is commonly used for hardcover books. Mass market paperbacks match duodecimo.
In the UK, a common paperback size is B-format, used by publishers like Penguin Classics. This differs from A-format, which is slightly narrower than ISO B6, and C-format.
Historically, terms like octavo, quarto, and duodecimo were used to describe book sizes, and they are still used today for older books.
Australia uses similar paperback sizes to the UK, but C-format is larger. There is also a B+ format.
In Japan, book construction uses a mix of ISO A-series, JIS B-series, and traditional Japanese paper sizes. A- and B-series signatures are folded from sheets slightly larger than ISO A1 and JIS B1, respectively, and then trimmed to size. Common sizes are listed below.
Records
According to the 2003 Guinness World Records, the largest book in the world was Bhutan: A Visual Odyssey Across the Last Himalayan Kingdom by Michael Hawley. Its size is 1.5 meters × 2.1 meters (5 feet × 7 feet).
According to the 2007 Guinness World Records, the largest published book in the world was The Little Prince, printed in Brazil in 2007. Its size is 2.01 meters × 3.08 meters (6 feet 7 inches × 10 feet 1 inch).
According to the 2012 Guinness World Records, the largest book in the world was This the Prophet Mohamed, made in Dubai, UAE. Its size is 5 meters × 8.06 meters (16.4 feet × 26.4 feet). Even though it is larger than The Little Prince, the two hold separate records because This the Prophet Mohamed was not published.
The smallest book is Teeny Ted from Turnip Town, which measures 0.07 millimeters × 0.10 millimeters (0.0028 inches × 0.0039 inches). It is a micro-tablet book carved on a pure crystalline silicon page, measuring 70 micrometers by 100 micrometers. It was etched using an ion beam at Simon Fraser University, Canada.
The largest surviving medieval manuscript is the Codex Gigas, also known as the "Devil's Manuscript," with dimensions of 920 millimeters × 500 millimeters (36 inches × 20 inches).