• Individual HTML files within the eBook must be smaller than 30 MB. If an individual file is larger, split the HTML file into smaller files to meet the requirement.
• The eBook must contain fewer than 300 HTML files.

In addition, Amazon encourages you to review the entire book for:

• Missing content
  • Font files in the eBook with zero bytes
• Wrong content
• Typos and complete character support
• Alignment errors
• Forced typeface throughout the entire book (reflowable only) or correct font (fixed-layout)
• Image quality
• Proper paragraph spacing and indenting
• Forced font color or background color (reflowable only)
• Content accessibility errors, including:
  • Missing or improperly nested headings
  • Improperly described links
  • Insufficient contrast between text and background colors (WCAG standards recommends a minimum contrast ratio of 4.5:1)
  • Improperly structured data tables (see Create Simple HTML Tables)
  • Images missing text alternatives (see Use Supported Input Formats)

Testing Kindle eBooks

There are three ways to test your Kindle book before adding it to the Kindle store:

• Kindle Previewer. Publishers and self-publishers can test eBooks using Kindle Previewer, available for both Windows and Mac OS X. Kindle Previewer is a great way to test your eBooks for formatting issues, and preview how they will appear on the latest Kindle devices and applications. Download the most recent version of Kindle Previewer (Note: Older versions of Kindle Previewer don't support Enhanced Typesetting).
• KDP. For self-publishers, Kindle Direct Publishing accepts a variety of book formats and provides preview capability on the website. Learn more or sign up.
• Kindle Create. If you're a self-publisher using Kindle Create to build your eBook, you can preview it in the tool.

If you are testing a reflowable eBook that supports Enhanced Typesetting, you can use the thumbnail view in Kindle Previewer to review the overall layout, or use Auto-Advance to automatically flip through the book. You can also selectively preview pages that contain images, tables, lists, drop caps, and links, using the View All option in the top pane of Kindle Previewer to ensure that each of these elements appear and behave as expected. The Conversion Log shows any errors or warnings that arise due to Kindle conversion. Enhanced Typesetting warnings and errors are available for books written in all languages except Japanese, Simplified Chinese, and Russian. For more details on using Kindle Previewer, refer to the user guide available in the Help menu.

Note: Amazon no longer recommends sideloading eBooks to devices for testing, because sideloading does not provide an accurate preview of Enhanced Typesetting features.

When you preview your book, use this checklist to confirm that your Kindle eBook doesn't contain blatant errors.

1. Open the book for the first time and go to the cover.
   • Cover: The Kindle book should have a cover.
   • Single Cover: From the cover, flip to the next page. There should not be another image of the cover page.
   
   
2. Go to the table of contents (where applicable).
   • On the table of contents page of your eBook, confirm that each item is clickable and links to the correct location in the book. There should be no page numbers in the ToC.
   • Repeat this process in the table of contents displayed in the left pane of the previewer.
   
   
3. Go to any location in the book (reflowable eBooks only).
   • Font size: Change the font size; the book font should change accordingly. Regular text should not be bold or italicized.
   • Typeface: Change the typeface; the book font should change accordingly. If you have designed your book to use only a specific font file, make sure that you have followed the guidelines for embedded fonts. Not following these guidelines could lead to the Kindle settings reverting to the customer's preferred reading font.
   
   
4. Go back to the first page and flip through every page of the book.
   • Images: Images should not be too small. Make sure that all text in images is legible. Large pictures should be scaled to fit the page and display in their entirety on one screen.
   • Tables: Tables should appear correctly. Make sure that all text in tables is legible.
   • Material only included with physical book: There should not be any references to material (such as a CD or DVD) that is only included with the physical book.
   • Background settings (reflowable eBooks only): Confirm that your text is legible in all background color modes (white, black, mint, and sepia).
   • Magnification (fixed-layout only): Activate pop-ups/panel view and check that all text content and/or panels have corresponding magnification, no content is overflowing the edge of the screen, and magnified reading order is correct.
   
   
5. To ensure a high-quality experience for all readers, Amazon recommends testing the accessibility of your book. Tools for checking content accessibility will vary based on your book format.
   • Word: Use the built-in Accessibility Checker within Microsoft Word
   • PDF: Use the built-in Accessibility Checker within Adobe Acrobat Pro
   • EPUB: Use the ACE Accessibility Checker from the DAISY Consortium
   • HTML: Convert your HTML file to Word and review content accessibility with the Microsoft Accessibility Checker.
     
     Amazon recommends resolving all accessibility errors before uploading your manuscript to Kindle.