In book production a folio is the page number as it is printed on the page. It is a typographic element with a position, a size and a typeface, not just a count. A folio moved to the foot of the page is called a drop folio, and several kinds of page carry no folio at all while still being counted in the sequence.
The word has a second, older meaning that causes constant confusion, covered below.
The Definition
New Hart's Rules is explicit that the term does double duty: "The term folio has two meanings in print production: it is used of the sheets of a script and also of the page number as a designed element on a typeset page."
The Chicago Manual of Style's first edition, published in 1906, gave the definition that still holds, along with its companion term, at rule 272: "A folio is a page-number. Even numbers are placed on the verso; odd, on the recto. A drop-folio is a page-number placed at the bottom of a page."
That even-verso, odd-recto pairing is not a convention anyone chose. It falls out of how a bound book works: a recto is always odd and a verso always even.
Where Folios Sit
New Hart's Rules describes the two standard positions: the folio "usually appears at the outer top edges of the spread, or centred at the foot."
Outer means mirrored, not fixed. On a right-hand page the folio sits toward the right edge, on a left-hand page toward the left, so it always falls at the outside of the spread where a thumb finds it. Centring at the foot is the quieter alternative and is common in fiction.
Printers historically described the same arrangement in setting terms. De Vinne, in 1904: "The figures for odd pages, as 1, 3, 5, 7, etc., are set at the end of the line; the even pages, 2, 4, 6, 8, etc., are set at the beginning of the line."
Pages With No Folio
This is the part that surprises people, and the principle behind it is worth stating clearly: the folio is suppressed, not the number. New Hart's Rules: "All pages are counted in the pagination sequence, but the folio is not shown on some pages."
The pages that conventionally show none:
- some front matter pages, typically the half title, title, copyright, dedication and epigraph
- blank pages
- pages given over entirely to an illustration, figure or table
- turned pages, meaning those printed in landscape
Chapter openings are the interesting case, because they are usually a compromise rather than a suppression. New Hart's Rules: "The first page of a new chapter lacks a running head, and the folio (page number) is either omitted or appears at the foot of the page (as a drop folio), even when on other pages it falls in the head margin." The reason is simply that a folio in the head margin would collide with the chapter's display heading, and with whatever opens the text beneath it, such as a drop cap.
De Vinne stated the same practice as a rule: "The proper page figures should be put at the foot of every page that has a lowered chapter heading or a cut at the head of the page."
He also had little patience for dropping folios altogether, calling the fashion for omitting all page figures a novelty that "gives needless trouble to the folder as well as to the reader." The folder was the person assembling the printed sheets, who needed the numbers to work.
A Note on "Blind Folio"
You will see an unprinted-but-counted page number called a blind folio. It is widely used in the trade, but I could not verify the term in any style authority. New Hart's Rules describes the practice without naming it, and the 1906 Chicago manual defines drop folio but not blind folio. Treat it as trade vocabulary rather than a term you can cite.
The Other Meaning
Outside page numbering, folio refers to a sheet of paper folded once, and by extension to a large book format made that way. This is the sense in "First Folio". It also describes a leaf of a manuscript, which is why archival references cite folio numbers rather than page numbers.
The two senses have nothing to do with each other in practice. If someone asks about a book's folio, establish which they mean before answering.
Doing This in Deckle
Deckle's page number position setting offers three choices: Outer, which is the default and mirrors across the spread, Center, and Inner. Outer and centre match the two positions New Hart's Rules describes.
Folios can be turned off entirely with the page numbers toggle. Deckle also applies the chapter-opening convention automatically: a chapter's first page carries no running head, and blank pages inserted to push a chapter onto a right-hand page are left completely bare.
The numbering itself follows the standard two-sequence scheme, with front matter in roman numerals and the text restarting at arabic 1. For the whole scheme in one place, see how to number the pages of a book.
Common Mistakes
- Thinking an unnumbered page is uncounted. It is counted. Only the printed figure is suppressed.
- Reporting missing numbers as a fault. Gaps in the printed sequence are correct where blanks and full-page images fall.
- Setting folios inner. Possible, but they end up in the gutter where they are hard to see.
- Putting a folio in the head margin of a chapter opening. It collides with the heading. Drop it to the foot or omit it.
- Confusing the two meanings. Page number versus sheet format.
FAQ
Q: Is a folio the same as a page number? A: In book production, yes, with the emphasis on it being a designed element rather than a raw count.
Q: What is a drop folio? A: A page number moved to the foot of the page, used most often on chapter openings where a header-position number would clash with the heading.
Q: Should folios go at the top or the bottom? A: Either. New Hart's Rules gives outer-top and centred-foot as the two standard positions.
Q: Why do some pages have no number? A: Because printing one would be intrusive or pointless: blank pages, full-page images, and most front matter display pages.
Q: Do ebooks have folios? A: Not meaningfully. A reflowable file has no fixed pages, and retailers ask that page numbers be removed from ebook contents lists.