KDP Interior PDF Checker

No. The whole check runs in your browser: the file is read from your own disk into your own memory, and nothing about it is sent to us or to anyone else. There is no account and no upload endpoint, because there is no request that could carry one. We hold ourselves to it with an automated test that fails our build if this page ever makes a network request carrying your file — the claim is checked by machine, not promised in marketing copy.

No, and nothing that reads only your interior file could tell you that. These checks cover the properties of the PDF itself: page geometry, page count, image resolution, embedded fonts, file size. Amazon's own review also reads PDF/X-1a conformance and colour output intent, where your live content sits inside its margin table, your cover, your metadata, and the content of the book. A clean report is a statement about our checks, not a decision by Amazon.

Because a print run is a single physical setup. A book that is 6 by 9 inches for a hundred pages and 8.5 by 11 for the last fourteen cannot be trimmed as one book, so the file is refused. This is the most common way an interior fails and it is almost always accidental — a page inserted from another document, a title page exported at Letter, a cover page left in the interior file. We measure every page, never a sample, and tell you exactly which ones differ.

An image inside a PDF has no DPI of its own. It has a pixel size, and the page says how big to draw it, so the resolution that actually prints is the pixel width divided by the printed width in inches. A 2,000-pixel-wide image placed across 4 inches prints at 500 DPI; the same file stretched across 10 inches prints at 200 and will look soft. We follow each image through the page's transformation matrix to find the size it is really drawn at, including images nested inside reusable form objects, then divide. KDP asks for 300 DPI.

It means the PDF names a typeface but does not carry it, so whatever opens the file has to substitute something. On your own machine the substitute is the font you designed with, so the file looks right to you and wrong to everyone else, including the press: line breaks move, spacing changes, and a puzzle grid built around a monospaced figure stops lining up. Every layout tool has an embed-fonts option. One limit worth stating: we can tell you a font is embedded, but not whether its licence permits embedding — that is a question about your licence, not about your file.

Only if something is meant to run off the edge of the page — a full-page background, a photo that touches the trim. Most puzzle and low-content interiors do not need it, and adding it wrongly is worse than not having it at all. KDP's interior bleed is not a uniform border: it extends the top, the bottom and the outside edge, never the gutter, because the gutter edge is bound. So a bleed page is 0.125 inches wider and 0.25 inches taller than the trim, not 0.25 inches on both. A page that is 0.25 inches larger on both axes is cover bleed applied to an interior — the single most common version of this mistake, and one this checker names specifically.

24 to 828 pages for a black-ink interior, 72 to 600 for standard colour, and 24 to 828 for premium colour, as published in KDP's trim, bleed and margin specifications. Two caveats we would rather state than hide: those ceilings assume white paper, and the largest trims are tighter still — an 8.5 by 11 inch book caps at 590 pages. We check against the more permissive figure, so a pass here means not definitely out of range rather than accepted.

Safe margins and the gutter, cover geometry, and PDF/X-1a conformance. Margins are the interesting omission: KDP's inside margin grows with page count and alternates sides between odd and even pages, and checking it honestly needs the true ink bounds of everything on the page. A browser can see where images sit but not where every vector stroke ends, so a margin verdict from here would quietly pass a book whose puzzle grid runs into the binding. We would rather ship no margin check than an unreliable one.

No, and it would be misleading to try. A cover is a single wrapped sheet whose correctness depends on your page count and paper stock — spine width, spine-text clearance, the barcode keep-out area — none of which is in the cover file itself. Work the dimensions out with the free KDP Cover Size Calculator, or generate a print-ready guide with the KDP Cover Template Generator.

KDP's own upload limit is 650 MB and we check against it. In practice the constraint here is your device, not the tool: page geometry is measured on every page however long the book, while the expensive per-page content inspection is sampled on very long books so the page stays responsive. When that happens each affected result says exactly how many pages it was based on, rather than implying it read the whole book.