Start with the final book specifications.
Before exporting anything, confirm the trim size, paper type, ink choice, binding format, and whether the interior needs bleed. Those choices determine the page size, margin requirements, spine width, and sometimes whether one file can serve both paperback and hardcover.
Do not build the cover from an estimated page count unless you are prepared to rebuild it. Final page count drives spine width, and even a small interior change can move the cover out of tolerance.
Use a stable layout, not a visual patchwork.
A production PDF should come from a document with consistent styles, predictable spacing, and deliberate page setup. Files built from scattered text boxes, manual returns, pasted images, and improvised spacing are more likely to break during export or revision.
For fiction, consistency matters: chapter openings, running heads, page numbers, front matter, blank pages, and section starts should follow a system. For illustrated books, image size and placement should be controlled rather than dragged into place by eye.
Check margins, gutter, and live text before export.
Live text should not sit close to the trim edge. Page numbers, running heads, captions, footnotes, and decorative text are easy to overlook because they appear secondary. KDP does not treat them as secondary if they are outside the safe area.
The gutter should be checked after the final page count is known. A manuscript that grows during edits may need a different inside margin than the early draft.
Embed fonts and preserve the intended appearance.
Fonts should travel with the PDF so the printed file does not substitute a different typeface. This matters for both interiors and covers, especially when a layout uses display fonts, small caps, ornaments, or nonstandard characters.
Bad exports can flatten, rasterize, substitute, compress, or shift elements in ways that are not obvious until preview. The fact that a PDF opens is not proof that it is print-ready.
Use images at the size they will actually print.
Image resolution should be judged at final print size. A small image may look sharp in a design window and still fail when stretched across a full page or wraparound cover. Screenshots and social-media images are common sources of weak print output.
Full-bleed images need extra image beyond the final trim. If the artwork stops exactly at the page edge, trimming can expose a thin white line.
Review the PDF as a book, not just as pages.
Scroll through the PDF, but also review spreads. Check odd and even pages, title page placement, chapter starts, blank pages, widows and orphans, image alignment, running heads, and whether the back matter begins where it should.
Then use KDP’s preview process carefully. If the previewer reports a warning, treat it as a production clue, not an annoyance to click past.
Need a file checked?
If you have already tried to solve the problem and KDP is still warning or rejecting the file, send the trim size, page count, paper choice, rejected PDF, and the exact warning. We can tell you whether it needs a narrow correction or a deeper rebuild.