22-Point EPUB Formatting Checklist Before Upload

A formatted EPUB that passes this checklist will pass technical validation on KDP, Apple Books, and Draft2Digital. The items are grouped by category — work through each section before uploading, even for re-uploads after minor changes. A file regenerated after a small edit can introduce new structural issues the original didn't have.

Manuscript & Content

Double spaces removed — find-and-replace " " (two spaces) with " " (one space) throughout
Straight quotes converted to curly quotes, or left straight if your house style requires it — no mix of both
Encoding artifacts removed: no replacement characters (□), stray byte-order marks, or Windows-1252 characters in a UTF-8 file
Empty paragraph tags deleted from HTML chapter files — use CSS margin for spacing, not blank <p> tags
Zero-width space characters (U+200B) searched and removed from all chapter files
Front matter complete: title page, copyright page, dedication (if applicable)
Back matter complete: author bio, Also By page, acknowledgements (if applicable), mailing list CTA

Structure & Navigation

Table of contents present, correctly structured, and links resolve to correct chapter anchors
NCX file (toc.ncx) present in OEBPS folder and referenced in OPF manifest with correct media-type
nav.xhtml present for EPUB 3 files with a valid <nav epub:type="toc"> element
OPF spine lists all chapters in the correct reading order with no duplicate idrefs
All files listed in OPF manifest actually exist inside the EPUB ZIP package
No files exist in the EPUB package that are not declared in the OPF manifest

Metadata

dc:title populated and non-empty in content.opf
dc:creator populated with author name in content.opf
dc:language set to a valid BCP 47 code (e.g., "en" or "en-US") in content.opf
dc:identifier present — either a valid ISBN-13 or a unique UUID

Cover & Images

Cover image declared in OPF manifest with properties="cover-image" and correct media-type
Cover image minimum 1600px on the short side (KDP recommendation; Apple Books requires 1400px minimum)
All embedded images saved as JPG, PNG, or GIF — no EMF, WMF, BMP, or TIFF inside the EPUB
Image MIME types correctly declared in OPF manifest entries

Validation

EPUB validated with EPUBCheck (current version) — zero Critical and Error-level issues resolved
File opened in at least one e-reader app (Kindle Previewer or Calibre) to confirm visual rendering before upload
Total EPUB file size within platform limits (KDP: 650MB; Apple Books: 2GB; D2D: 300MB recommended)

Common questions

Does passing this checklist guarantee my book won't be rejected?

The structural and validation checks here prevent the vast majority of technical rejections. Content policy rejections — flagged cover images, prohibited content categories, or duplicate content flags — are outside the scope of this checklist and depend on each platform's content guidelines.

How often should I run through this checklist?

For every upload or re-upload, including minor updates. Even fixing a typo can introduce encoding issues or break the manifest if the EPUB is regenerated by a conversion tool. The checklist takes under 10 minutes once the workflow is established.

My EPUB passes EPUBCheck but still gets rejected — what's left to check?

EPUBCheck validates structural compliance. Platform-specific rejection causes that EPUBCheck doesn't catch include: cover image color profiles (Apple Books rejects CMYK), ISBN format in content.opf (Apple Books requires scheme="ISBN"), and duplicate content flags (KDP compares against existing ASINs). See the platform-specific checklists for Apple Books and KDP for those details.

Validate your EPUB before uploading

The free EPUB Validator catches structural, metadata, and navigation errors — the same issues this checklist covers — before they become platform rejections. No signup required.

Validate Your EPUB Free →

For a complete guide to EPUB structure and common errors, see the EPUB formatting guide and the EPUB errors reference.

Platform rejection guides: Why Amazon KDP rejects ebooks, Why Apple Books rejects ebooks, Why IngramSpark rejects books

Common EPUB errors: Missing NCX navigation table, Ghost spacing in e-reader previews

Common formatting mistakes: 10 EPUB formatting mistakes that cause rejection