How booklet imposition works — why page 1 prints next to the last page
Fold a stack of sheets in half and staple the spine and you have a booklet — but only if the pages were printed in an order that looks completely wrong laid flat. Working that order out is called imposition, and it is the job the PDF booklet tool does. This guide explains the logic so you can check its work and print zines, programmes and manuals on an ordinary printer.
What imposition is
Imposition is arranging a document's pages on the printed sheets so that, after folding and cutting, they read in order. A saddle-stitched booklet is the simplest case: each sheet is printed on both sides with two pages per side, folded once, and nested inside the others. Commercial printers impose 8, 16 or 32 pages per sheet in patterns that fold several times; the principle is the same.
Working out the order
For an n-page booklet (n a multiple of 4), the outermost sheet carries page n on the left and page 1 on the right of its outside face, and pages 2 and n−1 on its inside face. The next sheet inward carries n−2 and 3 outside, 4 and n−3 inside. Each sheet's four pages always sum to 2n + 2. An eight-page booklet therefore prints as: sheet 1 front 8|1, back 2|7; sheet 2 front 6|3, back 4|5. Stack the sheets in order, fold, and pages 1 to 8 appear in sequence. The pairs that sit side by side (8|1, 2|7) are the ones that look wrong on the flat sheet and are exactly right in the fold.
Why multiples of four
Each sheet contributes four pages, so a booklet's page count is always a multiple of four. A 10-page document needs 12 slots: the tool pads the end with blank pages, and printers put the blanks at the back or use them for notes. A 13-page document wastes three; sometimes it's worth trimming or adding a page to land on 12 or 16. Long documents fold badly as one saddle-stitched block — beyond about 60 pages the inner sheets stick out and the spine won't lie flat; they are printed as several signatures and bound, which is a different imposition.
Printing and folding at home
- Impose the PDF into two-page spreads on landscape sheets (A4 landscape makes an A5 booklet; Letter makes a half-Letter one).
- Print double-sided with the printer set to flip on the short edge, so the back of each sheet is the right way up. Print one sheet first to check.
- Keep the sheets in order, fold the stack in half together, crease firmly.
- Staple through the fold (a long-arm stapler, or open a normal one flat over a cork mat), or sew with thread for a nicer finish.
The N-up tool makes plain multi-page sheets when you want handouts rather than a fold; the print sheet tool handles photos.
Creep, margins and other real-world details
Paper has thickness, and in a thick booklet the inner pages push outward at the fore-edge — creep — so their outer margins look narrower after trimming. Professional imposition shifts inner spreads inward by a fraction of a millimetre per sheet to compensate; at home, on up to five or six sheets, it's invisible. Give the inner margin (the gutter, at the fold) a little extra width so text doesn't dive into the spine, and keep important content away from the trim edge. Page numbers help readers and you; the crop tool removes an unwanted border before imposing.
Sources and further reading
The claims in this guide rest on these references, which were checked when the guide was last updated. Spotted an error? The contact page says how to report it.