Uploading a book to KDP should be the final confirmation that your files are ready, not the first time you discover how they behave as a printed book.
A manuscript can look correct in Word or a PDF reader and still contain problems that become obvious only after it is interpreted as a book interior. The safest workflow is to inspect the file as a reader and as a printer before uploading it.
Confirm the trim size first
Your interior page size must match the trim size selected for the book. A 6 × 9 inch book needs a 6 × 9 inch interior unless the file includes bleed, in which case the page dimensions must include the required bleed allowance.
Do not resize the PDF after export simply to make the dimensions match. Scaling can alter text size, image quality, margins, and line breaks.
Check inside and outside margins separately
The inside margin sits beside the binding. It normally needs more space than the outside margin because part of the page becomes less visible when the book is opened.
Review several spreads rather than checking only one page. Look for:
- text moving too close to the gutter;
- headings with inconsistent alignment;
- page numbers entering the safety margin;
- full-page elements that stop short of the intended bleed.
Flip through the complete book
A numerical report can identify measurable problems, but it cannot replace a visual review. Flip through the pages in reading order and watch for abrupt changes.
Common visual problems include unexpected blank pages, chapters starting on the wrong side, isolated headings, inconsistent headers, and images that shift between otherwise similar pages.
Verify fonts and images
For a print-ready PDF, confirm that fonts are embedded. Missing fonts can be substituted during processing and may change line wrapping or the appearance of the text.
Images should also have enough effective resolution for their printed size. Enlarging a small image inside a document does not add detail; it only spreads the existing pixels over a larger area.
Inspect the cover as one measured file
A paperback cover is not just a front cover. The uploaded file contains the back cover, spine, front cover, and bleed in a single spread.
The required width depends on the trim size, page count, paper type, and binding. Recalculate the cover after any page-count change because even a small change can affect the spine width.
Make the final upload boring
The best upload is uneventful. Your file passes processing, the preview confirms what you already saw, and you can focus on the book rather than another correction cycle.
PreviewBound’s interior checker helps you inspect trim, margins, page spreads, and Author Proof before the file reaches KDP.