Formatting a book for KDP is really two related but distinct tasks: preparing a print interior that will sit correctly on a physical page, and preparing an ebook file that will reflow correctly across dozens of screen sizes. Authors who treat these as interchangeable often end up with a paperback that looks cramped or an ebook with strange spacing and broken navigation.
This guide walks through what each format actually requires at a conceptual level, so that when you sit down with KDP’s current upload tools and file-preparation documentation, you understand what you are looking at and why it matters.
Print vs ebook: two different problems
A print book is a fixed object. Every page is the same size, the text sits in the same place relative to the edge of the paper on every page, and the reader never resizes anything. An ebook, by contrast, might be read on a six-inch e-reader, a phone, a tablet or a desktop app, often with the font size, spacing and even the screen orientation changed by the reader.
This is why print formatting is about precise, fixed measurements, while ebook formatting is about clean, flexible structure. A print file that looks perfect on your screen might have the wrong margins for the printer. An ebook file formatted like a print document, with manual tabs, forced page breaks and empty paragraphs for spacing, will often look chaotic once a reader changes the font size.
Trim size
Trim size is the finished page size of a printed book, expressed as width by height. It affects almost every other print decision: margins, gutter, font size and how many pages your manuscript becomes. Trim size should generally be chosen to suit the genre and the manuscript, not picked at random once the writing is finished.
KDP supports a defined set of trim sizes for paperback and, where available, hardcover. Because supported sizes can be added or changed, check the current list on KDP’s paperback and hardcover formatting pages before locking in a page design. For more on choosing a size in the first place, see what size should my paperback be?
Margins
Margins are the white space around the text block on each page. In print, margins have to do real work: they keep text away from where the book will be trimmed, they leave room for a reader’s thumbs, and they interact with the gutter to keep text readable near the spine.
Margins that are too narrow can cause text to feel cramped or, in the worst case, to be trimmed off during printing. Margins that are too wide waste space and can make a book feel padded. KDP’s formatting documentation sets out minimum margin requirements that vary with page count, so check the current figures rather than reusing a template from an old project without checking it still applies.
Gutter
The gutter is the extra margin allowance on the inside edge of each page, closest to the spine. Because a bound book curves slightly at the spine, text placed too close to it becomes hard to read, especially in thicker books. The gutter compensates for that curve.
Gutter requirements typically increase with page count, since a thicker book curves more at the spine. This is one of several reasons print layout should be finalised once the manuscript length is close to final, rather than at an early draft stage.
Bleed
Bleed refers to artwork or colour that needs to extend all the way to the trimmed edge of the page, with no white border. It matters for covers, and for any interior images that are meant to fill the page edge to edge. Files without correctly set-up bleed can end up with a thin white line at the trimmed edge, or important content cut off.
Most straightforward text-only interiors do not need bleed at all. It becomes relevant mainly for illustrated books, workbooks with full-page graphics, or covers, where KDP’s specifications describe exactly how much extra area to include.
Page numbers, headers and footers
Page numbers, running headers and footers are conventions that make a printed book easier to navigate. Common practice is to omit numbers from part-title and chapter-opening pages, and to use a consistent, unobtrusive header style, often the book title on one side and the author name or chapter title on the other.
These are stylistic choices rather than fixed rules, but consistency matters more than any particular convention. A reader should never be able to tell that the numbering scheme changed halfway through the book.
Chapter openings
Chapter openings typically start on a fresh page, often with extra white space at the top (a "drop" before the chapter title begins) and sometimes with a decorative first letter or ornament. This is largely a design decision, but it should be applied consistently across every chapter using paragraph and page-break styles, not by hand-adjusting spacing on each page, which becomes fragile the moment anything else in the manuscript changes.
Fonts
For print, font choice affects readability, page count and the overall feel of the book: serif fonts are the long-standing convention for body text in fiction and narrative non-fiction, because serifs tend to help the eye track along a line of small print. For ebooks, the reader’s device or app often overrides your font choice entirely, so the more important thing is applying consistent paragraph and heading styles rather than manually selecting fonts throughout.
Whichever font you use, make sure it is properly licensed for the type of publishing you are doing. Free fonts are not automatically cleared for commercial use, and checking the licence takes a few minutes.
Images and resolution
Print images need to be high enough resolution to look sharp on paper, which is a higher bar than looking sharp on a screen. A photo that looks fine at typical screen size can look blocky or blurred once printed at a larger page size. For ebooks, the opposite problem exists: overly large image files can bloat the file size and slow down page loads without adding visible quality on a small screen.
For example, an author preparing an illustrated non-fiction title found that photographs pulled from a website looked sharp on their laptop but printed fuzzy in a physical proof copy, because the source images were far lower resolution than the printed page required. Ordering a proof copy before finalising the print run is the most reliable way to catch this kind of problem.
Front matter and back matter
Front matter typically includes the title page, copyright page, dedication and table of contents, usually in that broad order. Back matter can include an author’s note, acknowledgements, a call to action such as a mailing list sign-up, and details of other books by the author.
These pages are often skipped in early drafts and then rushed at the last minute. Because they are the first and last thing a reader sees, it is worth giving them the same care as the main text, particularly the copyright page, which typically needs to include correct rights information and, where used, ISBN details.
Preparing a PDF for print
Print interiors are usually submitted as a single, correctly sized PDF with fonts embedded, so that the file displays identically on any computer, including the printer’s systems. An unembedded font can silently substitute a different font at the printing stage, changing line breaks and page counts without warning.
Most word processors and design tools have an "export" or "save as PDF" option with settings for embedding fonts and setting page size precisely; check that these are configured correctly rather than relying on default export settings, which are not always print-ready.
Ebook file formats currently supported
Amazon has, over time, supported a small number of ebook file formats and its own internal formats for Kindle devices and apps, and has also changed which formats authors can directly upload. Because this has shifted more than once, do not rely on a remembered file format; check KDP’s current ebook file-format guidance before preparing your manuscript.
Reflowable ebooks
Most fiction, memoir and general non-fiction should be prepared as a reflowable ebook, meaning the text adapts to whatever font size and screen the reader chooses, rather than being locked to a fixed page layout. Reflowable files are built from properly applied paragraph and heading styles, not manual line breaks or spacing, so that the underlying structure can adapt cleanly.
A working table of contents, built from actual heading styles rather than a manually typed list, is one of the most common places reflowable ebooks go wrong. If chapter headings are not marked with a genuine heading style, navigation can fail even though the text itself reads fine.
When fixed-layout is the right choice
Fixed-layout ebooks preserve an exact page design, similar to a PDF, and are typically used for picture books, heavily illustrated non-fiction, or books where the layout itself carries meaning. They trade the flexibility of reflowable text for visual precision, and they generally take more technical work to prepare correctly. If your book depends on precise image and text placement, it is worth budgeting extra time, or professional help, for this format.
Using preview tools before publishing
KDP provides an online previewer that shows how both print and ebook files will actually look once processed, which is different from how they look in your word processor. Checking every chapter opening, the table of contents, and a sample of pages throughout the book in the previewer, rather than only the first few pages, is the single most effective habit for catching formatting problems before publication.
Common upload errors
Typical upload errors include margins or bleed that do not meet the platform’s current requirements, fonts that are not embedded in a print PDF, image resolution that is too low for the chosen trim size, and ebook files with broken or missing navigation. Most of these are flagged during the upload and preview stage, which is exactly why that stage should never be skipped.
Common mistakes
- Formatting print and ebook as one identical file. Print and ebook have different requirements; a file designed for one rarely works well for the other without separate preparation.
- Manually spacing an ebook with tabs and blank lines. Manual spacing collapses or multiplies unpredictably once a reader changes font size; use paragraph styles instead.
- Finalising page layout before the manuscript is locked. Any later text change can shift line and page breaks, so leave final layout until editing is complete.
- Skipping the online previewer. Files can look correct in a word processor and still display incorrectly once processed for print or Kindle.
- Using unlicensed fonts or low-resolution images. Both can cause rejected files, poor print quality or, in the case of fonts, licensing problems.
Frequently asked questions
Can I use the same file for print and ebook?
Not usually. Print files need fixed page dimensions, margins, gutter and bleed, while ebook files need to reflow, so they are normally prepared as separate files from a shared manuscript.
Do I need special software to format for KDP?
Many authors format successfully in standard word processors using proper heading and paragraph styles; more complex books, especially illustrated ones, often benefit from dedicated formatting or design software or professional help.
How do I know if my formatting is correct before publishing?
Use KDP’s current online previewer for both print and ebook files, check a range of pages rather than just the opening, and order a physical proof copy for print books before finalising.
Why does my page count keep changing?
Page count shifts whenever text, font, margins or trim size change, because each affects how much text fits per page; finalise layout only once the manuscript itself is complete.