Self-Publishing Guide — Best eBook Formats for Amazon, Apple and Google
Your manuscript is done. Months (or years) of writing, editing, and rewriting — and now you need to turn it into an eBook that looks professional on every platform. Amazon KDP, Apple Books, Google Play Books, Kobo Writing Life, and Barnes & Noble Press each have their own format requirements, file size limits, and cover image specifications. Getting these wrong means rejection emails, broken formatting, or your book looking amateurish next to traditionally published titles. Here's everything you need to know.
Format Requirements by Platform
Amazon KDP (Kindle Direct Publishing): Accepts EPUB, DOCX, KPF (Kindle Package Format via Kindle Create), PDF, and plain HTML. Amazon converts everything to their internal Kindle format during upload. As of 2023, Amazon stopped accepting MOBI uploads. The best format to upload is EPUB — it gives you the most control over formatting, and Amazon's converter handles EPUB-to-Kindle conversion most reliably. DOCX works for simple books but can produce unpredictable results with complex formatting.
Apple Books (via Apple Books for Authors or Distributor): Requires EPUB only. Apple has strict EPUB validation and will reject files with errors that other platforms accept. Your EPUB must pass the EpubCheck validator. Apple supports both EPUB 2 and EPUB 3, but EPUB 3 is strongly recommended for new titles — it supports better typography, embedded fonts, audio, video, and JavaScript interactivity.
Google Play Books: Accepts EPUB and PDF. For reflowable text books (novels, non-fiction), EPUB is required. PDF is only appropriate for fixed-layout content like graphic novels or textbooks. Google's EPUB validation is less strict than Apple's, but a clean, valid EPUB will always produce better results. Kobo Writing Life: Accepts EPUB and DOCX. EPUB is preferred. Barnes & Noble Press: Accepts EPUB, DOCX, and PDF. Again, EPUB gives the best results.
The Bottom Line on Formats
Create one clean EPUB file and it works everywhere. Every major platform accepts EPUB. Amazon converts it to Kindle format automatically. Apple, Google, Kobo, and Barnes & Noble use it directly. Maintaining a single EPUB source file is far easier than managing separate formats for each platform.
Manuscript Preparation Tips
The quality of your eBook depends heavily on how well your manuscript is prepared before conversion. Use styles consistently in your word processor — Heading 1 for chapter titles, Heading 2 for section headings, Normal/Body for paragraphs. Don't manually format headings by making text bigger and bold — use actual heading styles. eBook converters rely on these styles to create the table of contents, navigation, and proper formatting.
Use paragraph spacing, not blank lines, to separate paragraphs. Multiple blank lines in a manuscript create inconsistent spacing in eBooks because e-readers handle whitespace differently. Set paragraph spacing in your styles (6pt after, for example) and use a single line break between paragraphs. For scene breaks, use a horizontal rule or three centered asterisks — don't rely on blank lines, which may collapse or expand unpredictably.
Embed images at reasonable resolution. For a standard eBook, images should be 1000-1500 pixels on the longest side and under 500 KB each. Higher resolution wastes file size (and Amazon charges delivery fees based on file size for some pricing tiers). Lower resolution looks pixelated on high-DPI tablet screens. Save images as JPG for photographs, PNG for charts, diagrams, and images with text.
Cover Image Requirements
Every platform requires a cover image, and each has slightly different specifications. Amazon KDP: minimum 625 x 1000 pixels, recommended 2560 x 1600 pixels, ideal ratio 1:1.6, maximum 50 MB, JPEG or TIFF. Apple Books: minimum 1400 pixels on the short side, JPEG or PNG, no maximum size specified but keep it under 10 MB. Google Play: minimum 640 x 1005 pixels, recommended 2560 x 1600, JPEG or PNG. Kobo: minimum 1600 x 2400 pixels, JPEG or PNG.
For a cover that works everywhere without resizing: create it at 2560 x 3840 pixels (1:1.5 ratio) in RGB color mode, saved as high-quality JPEG. This exceeds the minimum requirements on every platform and looks sharp on high-resolution devices. If your cover designer delivers at a different size, you can convert the format or resize as needed. The cover is the first thing buyers see — it's worth getting right.
Why EPUB 3 Is the Future
EPUB 3 is the current version of the EPUB standard, and it's a significant upgrade from EPUB 2. It supports HTML5 and CSS3, which means modern typography (drop caps, ligatures, OpenType font features), responsive layouts, embedded audio and video, MathML for equations, SVG for scalable graphics, and JavaScript for interactive content. For a standard novel, these features don't matter much. But for textbooks, children's books, technical manuals, and interactive publications, EPUB 3 is transformative.
All major e-readers and apps now support EPUB 3. Amazon's Kindle format (KF8/AZW3) is based on EPUB 3 internally. Apple Books has full EPUB 3 support. Google Play Books supports most EPUB 3 features. If you're creating a new eBook, there's no reason to use EPUB 2 — author it in EPUB 3 from the start. Most modern EPUB creation tools (Sigil, Vellum, Atticus, Kindle Create) produce EPUB 3 by default.
Common Formatting Mistakes That Make Your Book Look Amateur
Forced line breaks: Using Shift+Enter to manually break lines causes text to break at wrong points on different screen sizes. Let the e-reader handle line wrapping. Tab characters for first-line indent: Tabs render inconsistently across e-readers. Use CSS text-indent in your styles instead. Spaces for alignment: Multiple spaces to center or align text will break on every device. Use proper CSS alignment. Hard page breaks everywhere: A page break before every section creates blank pages on some devices. Use them only for chapter starts.
Missing table of contents: Every eBook platform requires a navigational table of contents embedded in the EPUB's navigation document. A visible table of contents in the text is nice but not sufficient — you need the NCX (EPUB 2) or NAV (EPUB 3) table of contents that e-readers use for their built-in navigation menus. Most conversion tools generate this automatically from your heading styles.
Testing Your eBook Before Publishing
Never publish an eBook without testing it on actual devices or accurate emulators. Amazon: Download Kindle Previewer (free desktop app) and open your EPUB in it — it shows exactly how your book will look on every Kindle device and app. Apple: Open your EPUB in Apple Books on a Mac — what you see is what readers get. EPUB validation: Run your file through EpubCheck (free, open-source) to catch technical errors before any platform rejects it.
Things to check during testing: does the table of contents work and link to correct chapters? Do all images display at appropriate sizes? Is the text readable at different font sizes? Do chapter breaks appear where expected? Does the cover image display correctly? Are there any blank pages or missing content? If you have access to a physical Kindle, Kobo, or iPad, test on those too — emulators are good, but real devices occasionally reveal issues that previewer apps miss.
If your manuscript is in a format that your target platform doesn't accept, or you need to convert between formats during your testing process, the eBook converter handles conversions between EPUB, MOBI, AZW3, PDF, and FB2. Start with a clean EPUB, test thoroughly, and only convert to other formats when a specific platform requires it.
