FoldProof booklet guide
Booklet page order, blanks and saddle stitch explained
A folded sheet contributes four finished pages: two on the front and two on the back. That physical constraint is why a ten-page document becomes a twelve-position booklet instead of a ten-position one.
1. Start outside and work inward
For a left-bound eight-page booklet, the outer front is 8 | 1 and outer back is 2 | 7. The inner sheet is 6 | 3 and 4 | 5.
2. Mirror right-bound booklets
Right binding mirrors the left and right panels on every face. It does not merely reverse the source PDF or rename the page numbers.
3. Insert blanks explicitly
Round the source count up to a multiple of four. Mark each inserted position as a blank in the UI and proof instead of allowing an exporter to hide padding decisions.
4. Keep front and back identities
A useful proof names sheet number, face, physical panel, source page, rotation and offset. That makes a wrong output diagnosable before paper is wasted.
5. Preserve the original
Imposition should create a new PDF. Hash the source before and after export so the print transformation never becomes an accidental edit of the original document.