A print-ready PDF for KDP

“Print-ready” is not a format. A PDF is print-ready when four things are true of it: the page is the size of the finished book, the margins clear what the binding and the guillotine will take, every font is inside the file, and the images have enough pixels at the size they are printed. Amazon states the first three as numbers and the fourth as a guideline.

What it does not state, because they are conventions rather than requirements, is everything that makes the result look like a book. Those are at the bottom of this page.

The margins

Four of them, and they are not symmetrical. Outside, top and bottom are the same on every page. The inside, the edge nearest the spine, is wider, and it changes sides: on a right-hand page the spine is on the left, on a left-hand page it is on the right. That swap is called mirrored margins, and it is the single clearest difference between a book interior and a document exported to PDF.

The inside margin, by page count

A perfect-bound book does not open flat, and the thicker it is the less flat it opens. So the inside margin requirement rises in five steps:

The requirement that chases its own tail

Read the table again and the problem appears: the inside margin depends on the page count, the page count depends on the width of the text block, and the width of the text block depends on the inside margin.

There is no way to resolve that in one pass. You lay the book out at some assumed gutter, read the page count that comes out, and lay it out again at the gutter that page count requires, repeating until the band stops changing. Two passes is usually enough; three happens when the count lands within a page or two of a boundary.

The direction you iterate from matters more than the number of passes. Start at the widest gutter and come down. Every intermediate state then over-estimates the page count, so stopping early leaves a book with more inside margin than it needs. Start narrow and grow, and an early stop leaves a book with less. That error does not announce itself. It prints.

Bleed

Only if something is meant to touch the edge of the page. Amazon asks for 0.125″ (3.2 mm) on all sides, which means the PDF pages are a quarter inch larger than the trim in both directions, with the artwork running into that border. A book of prose has nothing to bleed and should not declare it: the only effect is to raise the margin minimums.

Fonts and images

• Every font embedded. No exceptions, including the one used for a single ornament. Subset them, meaning embed only the characters the book uses, or the file grows by several megabytes for no visible benefit.
• Images at 300 DPI at print size. Measured at the size on the page, not the size of the file. Amazon recommends staying under 600 DPI to keep the upload under 650 MB.
• No transparency surprises. Flatten anything that relies on a blending mode; print pipelines resolve them differently from screens.
• One page per page. Not spreads. The interior is a sequence of single pages; Amazon imposes them onto sheets itself.

Page count limits

24 pages minimum. 828 maximum, and only with black ink on white paper: cream paper caps at 776 and standard colour at 600, because a thicker sheet makes a thicker book. The full table is on the trim sizes page. Amazon also rounds the printed page count up to an even number, because a sheet has two sides.

What Amazon does not ask for, and a book needs anyway

Everything above produces a file that will be accepted. None of it produces a file that looks like a book. These are the conventions a typesetter applies that no specification mentions:

• Chapters open on a right-hand page, leaving blank left-hand pages where they fall, and those blanks carry no page number and no running head.
• Front matter is numbered in roman, and the arabic numbering restarts at 1 on the first page of the first chapter. That is why a novel’s story begins on “page 1” rather than on page 9.
• No widows and no orphans. A paragraph’s last line never sits alone at the top of a page; its first line never sits alone at the foot of one.
• The first paragraph of anything is not indented. Not after a chapter opening, a scene break, a block quote or an image. An indent signals continuation.
• The bottom margin is deeper than the top. Optically centred sits above geometrically centred, so a text block with equal margins looks as if it has slipped.
• Every page’s lines sit at the same heights. Hold the grid and an open spread reads as one object; break it and the two pages disagree in a way readers notice without being able to name.