Formatting is where a manuscript turns into a book, and it is the step where most first-time self-publishers lose a weekend. The good news is that the rules are precise, public and not that many. Here they are for KDP in 2026, print and ebook, with the actual numbers.
Print and ebook are two different problems
The single most useful thing to understand up front is that a print book and an ebook are formatted in opposite ways, and a file that is right for one is wrong for the other.
A print book is fixed. Every page is a precise physical size, the text sits inside precise margins, and you deliver a print-ready PDF where what you see is exactly what gets printed. An ebook is reflowable. There are no fixed pages at all, because the reader chooses the font and the text size, and the words rewrap to fit whatever device they are on. You deliver a file such as EPUB that describes structure, headings, chapters, paragraphs, and lets the reading app lay it out. Trying to force fixed page layout into an ebook is the most common formatting mistake there is.
Print: choose your trim size first
Trim size is the finished dimensions of the printed page. Choose it before you format anything, because every other number depends on it. The most common trim for a US paperback is 6 by 9 inches, and it is a safe default for a novel or most non-fiction. KDP offers others, from small mass-market sizes up to large formats, but pick one and commit, because changing trim size after you have laid out the interior means redoing the layout.
Print: margins and the gutter
Margins are the white space around your text. KDP sets minimums, and going under them gets your file rejected. The outside, top and bottom margins must be at least 0.25 inches, or at least 0.375 inches if your book uses bleed (more on bleed below).
The inside margin, called the gutter, is the one people get wrong. It is the space next to the spine, and it has to be larger than the others because the binding swallows some of the page, and it has to grow as the book gets thicker because thicker books curve more at the spine. KDP's current minimum gutter by page count is:
- 24 to 150 pages: at least 0.375 inches
- 151 to 300 pages: at least 0.5 inches
- 301 to 500 pages: at least 0.625 inches
- 501 to 700 pages: at least 0.75 inches
- 701 to 828 pages: at least 0.875 inches
These are minimums. Giving the gutter a little more than the minimum almost always reads better than sitting exactly on the line.
Print: bleed
Bleed is for ink that runs all the way to the edge of the page, full-page images or background colour. Printers cannot print reliably to the very edge, so they print slightly oversized and trim it down. If any element on a page touches the edge, you need bleed: extend that element 0.125 inches past the trim on the top, bottom and outside edges, not the spine edge. In practice that means a 6 by 9 book with bleed is laid out on pages that are 6.125 by 9.25 inches. If your interior is plain text with no edge-to-edge art, which most novels are, you do not need bleed at all, and it is simpler to leave it off.
Print: page count rules
KDP interiors must have an even page count, because every printed sheet has two sides, and between 24 and 828 pages. If your content lands on an odd page count, add a blank page. If you are over 828, you may need to split the book or move to a larger trim size.
Print: the details that separate a proof from a book
- Use an embedded, print-safe font at a readable size, commonly 11 or 12 point for body text. Embed the font in the PDF so the printer renders it exactly.
- Start chapters on a new page, and consider starting them on a right-hand (odd) page, which is the traditional look.
- Put page numbers and any running headers inside the safe margins, not down in the bleed zone.
- Include your front matter: title page, copyright page, and for many books a dedication and a table of contents.
Ebook: reflowable formatting
For the ebook, forget pages entirely. What matters is clean structure. Each chapter should be a real heading so the reading app can build a navigable table of contents. Paragraphs should use proper paragraph styling, not tabs or rows of spaces, which break when the text reflows. A single cover image goes at the front. Avoid fixed line breaks in the middle of paragraphs, avoid hard page breaks except between chapters, and test the file on more than one screen size, because a phone and a large tablet will lay it out very differently.
The mistakes that get a file rejected or printed wrong
- Margins or gutter under the minimum for the page count. The most common rejection.
- A print PDF whose page size does not match the chosen trim, or bleed declared but not actually extended to the edge.
- Fonts not embedded, so the printer substitutes something and the layout shifts.
- An odd total page count on a print interior.
- Tabs, manual spacing or fixed layouts in an ebook, which look fine on your screen and fall apart on the reader's.
Front matter, back matter and hardcovers
Two more things round out a print interior. Front matter is everything before chapter one: the title page, the copyright page, and often a dedication, an epigraph and a table of contents. Back matter is everything after the last chapter: an about-the-author page, an acknowledgements page, and often a short invitation to the reader to leave a review or find your other books. None of it is filler. The copyright page is a legal nicety, and the about-the-author page and the review invitation are quietly some of the best marketing in the whole book. If you publish a hardcover as well, the same interior rules apply, but the cover is built differently, with a wrap and sometimes a dust jacket, and the page-count minimums differ, so treat it as its own format rather than assuming the paperback files will simply carry over.
How Pressborn removes this pain
Formatting is exactly the kind of precise, mechanical work that should be automated, and it is what Pressborn's package builder does. You give it your manuscript and your choices, trim size and paper, and it builds the interior PDF to the target store's print rules, with the correct margins for your page count, and a reflowable EPUB for the ebook, in the same package.
It builds a separate package for each store you choose, KDP, IngramSpark, Draft2Digital, Apple Books, Kobo and Google Play Books, because their requirements are not identical, and a file that passes one can fail another. You still upload the finished files to your own store account, but you are uploading files that were built to pass, not a Word document you are hoping is close enough.
A cleanly formatted book starts with a clean manuscript, which is what the three editing passes are for. When the words are right, the formatting is the easy part. If you are still weighing the whole thing up, here is what self-publishing actually costs .