Printing a folded booklet from an ordinary PDF

Booklet printing is the one office task where doing it correctly by hand is genuinely difficult, and where getting it wrong wastes a whole print run.

The difficulty is not the printing. It is that the pages have to be placed on the sheets in an order that looks like a mistake right up until you fold the stack.

Why the order is strange

Take four sheets of paper, stack them, fold the stack in half. You have a sixteen-page booklet.

Now number the pages as a reader would encounter them, and look at what any single sheet carries. The outermost sheet holds page 1 and page 16 — the front and back covers — on the same side of the same piece of paper. Its reverse holds pages 2 and 15.

Work inwards and the pattern continues: the next sheet carries 14-3 and 4-13. The innermost carries 8-9, the only pair that is consecutive.

For an eight-page booklet the sheets read:

Sheet 1, front:   8 | 1
Sheet 1, back:    2 | 7
Sheet 2, front:   6 | 3
Sheet 2, back:    4 | 5

Nobody arrives at that by intuition, and the arithmetic changes with every page count. This rearrangement is called imposition, and it is exactly the kind of task worth handing to software.

Create PDF booklet calculates the page order and sheet layout locally, on landscape A4 sheets. Open the result to check it before you commit paper to it.

The multiple-of-four rule

Every folded sheet carries four pages — two on the front, two on the back. So a booklet’s page count is always a multiple of four.

A twenty-two page document becomes a twenty-four page booklet. Two pages will be blank, and the only real decision is where they go.

Filozy always adds them at the very end and has no setting to move them. For most documents that is fine. To put them somewhere else, add the blank pages where you want them in the app that made the document, so the file is already a multiple of four, then impose it. Two common choices:

• Before the back cover often looks more deliberate, leaving the final page as a proper closing page rather than stranding blanks after it.
• After the title page suits a document with a formal front matter convention.

Deciding deliberately is what separates a booklet that looks produced from one that looks like a print accident.

N-up is a different job

The same imposition tool usually offers N-up, and the two get conflated.

N-up places several pages on one sheet in ordinary reading order — 1 and 2 side by side, then 3 and 4. It is for saving paper, for handouts, for reviewing a deck. The output is read flat.

Booklet reorders and pairs pages for folding. The output looks wrong flat and correct folded.

Choosing booklet when you wanted 2-up produces a handout nobody can follow. Choosing 2-up when you wanted a booklet produces a stack that reads 1, 2, 3, 4 across a fold — which is to say, not a booklet at all.

Page numbers go on before imposition

This trips people up reliably, and the failure is expensive because you only notice after printing.

Add page numbers to the document while it is still in reading order. Add page numbers draws them into a separate saved copy; do that first, then impose the numbered file.

Number after imposing and you number the sheets — the first sheet gets a “1” that sits under page 8. The numbers will be wrong in a way that is hard to unpick, because the underlying page order is no longer the reading order.

The rule is simple: anything that refers to reading order happens before imposition. Numbering, headers, a table of contents.

Printing it

Imposition produces a PDF. Printing it correctly is a separate step with its own traps:

• Print double-sided, flipping on the short edge for a booklet folded like a book. Long-edge flipping inverts every second sheet. If your printer has no duplex, print odd sheets, reload, print even — and test the reload direction on two sheets before committing.
• Print at 100% on A4. The imposed file already has the correct geometry, and Filozy lays it out on landscape A4 sheets only.
• On US Letter, “fit to page” is fine. It shrinks each sheet by about 6%, and a printer that centres the shrunk sheet keeps the fold in the middle. Other scaling can shift the fold line, so the fold stops matching the page centres.
• Print one sheet first. Always. Fold it, look at it, then print the rest.

If one page comes out small

Booklet imposition does not turn pages. Each is scaled to fit its half of the sheet, so a wide page comes out upright but smaller: an A4 landscape page among portrait ones is drawn at about 48% of its size instead of 66%. A document that mixes orientations — a report with one wide table — can come out with that page much smaller than the rest.

To print it larger, turn that page before imposing. Rotate PDF changes the page dictionary without re-encoding anything, so correcting orientation first costs no quality and saves unpicking the imposed file later. The turned page then reads sideways in the booklet, so the reader turns it to read.

Checking the result before printing fifty copies

• Fold a single printed sheet and confirm the pages meet correctly at the fold.
• Check the page count is a multiple of four and the blanks are where you expect: at the back, unless you added them yourself.
• Read the inner spread — the innermost sheet is the only consecutive pair, so if 8 and 9 are not facing each other, the imposition assumed a different page count.
• Look at the margins near the fold. Content close to the spine disappears into it once folded, and no amount of careful printing recovers it.