00HOW OLD BOOKS WERE MADE

Fold the sheet,
find the book.

Hands folding a large sheet of cream handmade paper in half on a wooden table beside a row of old leather-bound books — AI-generated image, not a photograph of a real person or place.

Before the 1800s, a book began as a pile of big printed sheets.

Printers set several pages on each side of a sheet, then folded it and cut it into leaves. How many times they folded it gives the book its name: folio, quarto or octavo.

2° 4° 8°folded once, twice, three timesUpdated 16 October 2026

Try a fold

01Principles

Once makes a folio
Twice makes a quarto
Three times, an octavo
One sheet, many books

02THE SHORT ANSWER

A format is
a fold, not a size.

Catalogues write it as 2°, 4°, 8° and so on.
The number is how many leaves one sheet made.

THE FOLD

Count the folds

Fold a sheet once for two leaves, four pages: a folio. Twice gives four leaves, a quarto. Three times gives eight leaves, sixteen pages: an octavo.

Try a fold

THE SIZE

Usually, not always

A folio is likely to be bigger than a quarto, but the finished size depends on the sheet. The University of Liverpool says folios range from about 30.5 cm to 48 cm.

See the numbers

THE BINDING

Sections are sewn

The folded sheets form gatherings of leaves, and the gatherings are sewn together to make the whole book.

Read a catalogue

03A QUICK FOLD CHECK

How many times
was it folded?

Pick a format to see what one printed sheet became. The bar shows how large each leaf is compared with the original sheet.

Hand-press era books, roughly up to the early 1800s. Leaf sizes depend on the sheet the printer used.

Fold check

Choose a formatFolio (2°)Quarto (4°, 4to)Octavo (8°, 8vo)Sixty-fourmo (64mo)

Folio (2°)1 fold, 4 pages

Folded once to make two leaves, four pages. Each page is half the size of the sheet. A grand format, linked with bibles and works of history.

Quarto (4°, 4to)2 folds, 8 pages

Folded in half and in half again to make four leaves, eight pages. The Folger calls it a small, inexpensive format.

Octavo (8°, 8vo)3 folds, 16 pages

Folded three times to make eight leaves, sixteen pages. Smaller formats were quicker to print and used less paper and binding, so sold more cheaply.

Sixty-fourmo (64mo)Miniature

Some sheets were folded many more times. The University of Liverpool's smallest book, a miniature Bible history, is a 64mo.

Sources: University of Liverpool Special Collections, F is for Format; Folger Shakespeare Library, Plays in print; Jack Lynch, Literary Terms: Sheet.

04TWO NUMBERS WORTH KNOWING

Cheap folds vanish,
grand ones last.

One famous case shows how format shaped survival:
small quartos and a large folio.

Plays printed as quartos in the author's lifetime

The Folger says 18 of Shakespeare's plays were printed in his lifetime as quartos, sold in flimsy bindings or none at all. Some survive in only a single copy.

QUARTOS · FOLGER

220+

First Folios known to survive

Wadham College Library says there are at least 220 First Folios in the world. Its large, expensive format, probably kept in a library rather than carried, helped so many survive.

THE 1623 FOLIO · WADHAM COLLEGE

Wadham College Library notes the First Folio collected thirty-six plays, and almost twenty of them would not survive at all without it.

05READING A CATALOGUE ENTRY

Small symbols,
big clues.

Library catalogues for old books often note the format in the description. Here is how to read it.

Find the format mark
Look for 2°, 4°, 8° or 12° in the description field, or the forms fo, 4to, 8vo and 12mo.
Turn it into folds
2° is one fold, 4° two folds and 8° three. Higher numbers mean more folds and smaller leaves.
Check the measured size
Format is not a fixed size. Look at the height in centimetres as well, because sheet sizes varied.
Ask what it was for
Large books were made to be shown off or read by many; small ones to be carried and sold cheaply.

Hands sewing folded paper sections onto cords on a wooden bookbinder's sewing frame — AI-generated image, not a photograph of a real person or place.

06WHY FORMAT MATTERS

Luxury or
pocket money?

A row of old leather-bound books standing on a library shelf, from a tall folio down to a tiny pocket volume — AI-generated image, not a photograph of a real person or place.

Format hints at how a printer saw a book. Smaller formats could be printed more quickly and used less paper and less binding material, so they could be sold more cheaply. Paper was expensive, and Wadham College notes that the First Folio was a huge investment for its printers.

Format also hints at use. The University of Liverpool contrasts a two-volume Bible printed in Nuremberg in 1475, nearly half a metre tall, with a student's chemistry pocket-book of 1844 that is 17 cm.

07Questions

Questions people ask

What does folio mean?

A folio is a book made from sheets folded once, giving two leaves or four pages per sheet. Catalogues write it as 2° or fo. Each page is half the size of the original sheet.

What is the difference between quarto and octavo?

A quarto sheet is folded twice to make four leaves, eight pages. An octavo sheet is folded three times to make eight leaves, sixteen pages, so its leaves are usually smaller.

Is a folio always bigger than a quarto?

Usually, but not always. The finished size depends on the size of the sheet, which varied in the hand-press period. The University of Liverpool says folios range from about 30.5 cm to 48 cm.

What do 4to and 8vo mean?

They are short forms for quarto and octavo, also written 4° and 8°. You will see them in library and bookseller descriptions of old books.

How can experts tell how a sheet was folded?

Cataloguers use marks within the paper to work out how many times a single sheet was folded, according to the University of Liverpool's Special Collections.

08Sources

Fold the sheet,
find the book.