Impose a PDF two-up for duplex printing

2-up cut-stack imposition puts two book pages on each side of a sheet, ordered so the whole print run needs one cut and one stack: print double-sided, cut the pile in half, put the left pile on top of the right pile — and the book reads first page to last. Drop a PDF in below. It is rearranged in your browser and never uploaded.

Written by the person who built the thing · Last checked

Drop a PDF here, or click to chooseThe file is rearranged on this machine and never uploaded.

The file is rearranged on this machine and never uploaded. First time on a new printer, on one sheet’s worth of scrap and check which way your duplex flips before committing real paper.

Why the pages look shuffled — and why they must

A naive 2-up layout — pages 1 and 2 on the first side, 3 and 4 on the next — produces sheets that have to be sorted by hand after cutting, because every sheet's left half belongs to a different part of the book than its right half. Cut-stack order instead pairs page n with the page half a stack away, so the single cut leaves the left pile already sitting in reading order on top of the right pile. It is the same logic every print shop's imposition software uses, shrunk to a home printer.

Print two-sided, actual size

Flip on the edge the tool tells you — short edge for most printers, long edge if the test book's backs come out upside down. Never “fit to page”: the pages are already the size they should be, and scaling shrinks the margins twice.

One cut, straight down the middle

The tool tells you the distance in millimetres — for an A5 book on A4 sheets it is 105 mm. Cut the whole stack at once; a guillotine is ideal but a fresh blade and a straightedge will do for one book.

Left pile on top of right pile

That single stack is the book, in reading order. Take it straight to the binder — or a bulldog clip, for the honest home edition.

2-up cut-stack or fold-and-staple?

Questions people actually ask

Does my PDF get uploaded anywhere?

No. The pages are rearranged in your browser's memory and handed back as a download. Nothing crosses the network — this is deliberate, because the kinds of books people impose (manuscripts, theses, private chats) are exactly the kinds that should not sit on a stranger's server.

My book is A5 and my printer is A4 — does that work?

That is the standard case: two A5 pages sit on one A4 portrait sheet side by side. The output sheet is exactly twice your page size, whatever size that is — the tool reads it from the PDF.

Why are the page numbers out of order in the output?

Because each printed side must carry pages that end up half a stack apart after the cut. If the output read 1, 2, 3, 4 across its sheets, the cut piles would need sorting by hand. Print it, cut it, stack it — then it reads in order.

What does 'cut-stack' mean, exactly?

It is a print-trade term: the press prints a stack of sheets, one cut splits every sheet at once, and the resulting piles are stacked rather than interleaved. This tool reproduces that ordering for a single book on an office printer.

Can I impose a book that is already a spread PDF?

No — this expects one page per PDF page, the way books are exported. If your PDF has two book pages per page already, split it first, then impose here.

This imposer grew out of the one that prints WhatsApp chat books.

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