Kindle
Kindle EPUB Checker
Before uploading to Amazon KDP, check your EPUB against the rules KDP publishes. The checker requires a cover image marked inside the book and measures it against KDP's guideline of at least 1200 pixels in width or height, runs the EPUB structure checks (mimetype, identifier, manifest, spine, table of contents, well-formed pages), checks the title, language and author, and explains what the file's size means for KDP's delivery cost. Each rule links to the KDP help page it comes from.
Written by Jay Sudha · Published · Last updated
Input formats
Output formats
Common uses
- Check an EPUB before uploading to Amazon KDP
- Diagnose why a Kindle upload was rejected
- Check that the cover inside the book meets KDP's size guideline
- See what a file's size means for KDP's delivery cost
Limitations
- This tool is not endorsed by Amazon. Use it as a pre-check, not a guarantee that KDP will accept the book.
- KDP converts every EPUB for Kindle, and that conversion can raise issues not caught here; preview the book in Amazon's Kindle Previewer before publishing.
- The store cover you upload to KDP separately is not part of the EPUB, so it is not checked; KDP's sizes for it are shown for reference.
- The structure checks cover the rules EPUBCheck most often fails books on, not every rule.
Your e-book files, handled privately
This tool runs entirely in your browser. On this site, your files are not uploaded to a server. This tool does not remove DRM or bypass copyright protection. Only upload files you own or have permission to process.
Where the Kindle EPUB Checker fits in your publishing workflow
This tool is a pre-upload review step for authors and small publishers preparing an EPUB for Amazon KDP. Run it after your manuscript is exported as EPUB and before you submit, so you catch the problems KDP's help pages warn about rather than discovering them mid-upload. It reads one EPUB at a time and produces a report listing what passed, what needs attention, and which KDP page each rule comes from.
It suits a self-publisher finalizing a novel, an author re-uploading a corrected edition, or anyone given an EPUB by a designer or conversion service who wants an independent check.
It is not a converter or a KDP portal: convert your manuscript to EPUB first, and upload it to KDP yourself.
How the check runs and what it inspects
Drop your EPUB and read the report; the file is opened in your browser and never uploaded, which matters for unpublished manuscripts.
The report checks, in order: that a cover image is marked inside the book (KDP says every Kindle eBook must have one) and that it is at least 1200 pixels in width or height, read from the image file itself; the EPUB structure, from the mimetype file to well-formed pages, with every problem listed; and the title, language and author. Two notes follow for reference: the sizes KDP asks for the separate store cover, and the file's size with the delivery cost it implies on the 70% royalty option. Each line is a pass, warning, fail or note, and the report can be downloaded as text with the KDP sources listed.
Limits to keep in mind and mistakes to avoid
The most important caveat: this tool is not endorsed by Amazon. It applies rules from KDP's own help pages, read on 27 September 2026 and linked in the report, but KDP converts every book, and its conversion and quality checks can still raise problems this checker does not see. Treat a clean report as a strong pre-check, not a promise.
Two covers cause most confusion. The cover inside the EPUB is what this tool checks; the store cover is a separate upload that this tool never sees. The 1200-pixel guideline is written for reflowable books, so for a fixed-layout book, such as a comic or a children's picture book, the tool shows the cover's size and points you to KDP's fixed-layout guidance. Another pitfall is checking an old export: if you fixed something in your authoring tool, re-export and re-run so the report reflects the file you will actually upload.
It checks technical readiness, not content: typos, or a cover that is valid but wrong, still need your own eyes.
Reading the report and confirming before you upload
Work through the report top to bottom: fix any failed line first, starting with the cover and structure errors, then the warnings. Apply fixes in your editing tool or with the Add Cover and Metadata Editor tools, then re-run the check to confirm the problem is gone.
After the technical items pass, preview the book in Amazon's Kindle Previewer and do a short manual pass: tap through the table of contents, scan a few chapters on a phone-sized screen, and confirm the cover looks right at thumbnail size. The checker tells you the file meets the rules it checks; only a preview confirms it reads the way you intend.
Stores change their rules, so check the linked KDP pages whenever a number matters.
Frequently asked questions
Two covers are involved. The cover inside the EPUB should be at least 1200 pixels in width or height (KDP's image guidelines for reflowable books), and KDP says every Kindle eBook must have one. The separate cover you upload for the store page is ideally 1,600 × 2,560 pixels (width × height), at least 625 × 1,000 pixels, no more than 10,000 pixels on a side, JPEG or TIFF, and under 50 MB.
KDP publishes no maximum EPUB size. What size changes is the delivery cost: on the 70% royalty option, Amazon deducts a cost for each megabyte of the book as Amazon measures it, US $0.15 per MB on Amazon.com, with other rates in other marketplaces. The 35% option has no delivery cost. The checker shows the estimate for your file.
No. This tool cannot remove DRM or bypass copyright protection. Only upload files you own or have the right to publish.
No. The EPUB is examined in your browser. On this site, your files are not uploaded to our servers; the report is generated on your device.
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Tool last reviewed: September 27, 2026 · Report a problem