EPUB accessibility sounds like a niche technical topic, but if you sell ebooks on Amazon, Apple Books, or any major retailer, it directly affects your book's visibility and sales. Here's everything you need to know, explained without jargon.
What Is EPUB Accessibility?
An accessible EPUB is one that works for all readers, including people who use screen readers, magnification software, or other assistive technologies. In practice, this means your ebook file includes certain structural and descriptive elements that make the content machine-readable.
Think of it like curb cuts on sidewalks. They were designed for wheelchair users, but they help everyone: parents with strollers, delivery workers with carts, travelers with luggage. Accessible EPUBs similarly improve the reading experience for all users while being essential for readers with disabilities.
The Key Accessibility Standards
EPUB accessibility is governed by two main standards:
WCAG 2.1 (Web Content Accessibility Guidelines)
WCAG is the global standard for digital accessibility, maintained by the W3C. For ebooks, the relevant conformance level is AA, the middle tier. This covers requirements like:
- Sufficient color contrast between text and background
- Alt text for all meaningful images
- Logical reading order
- Navigable heading structure
EPUB Accessibility 1.1
This W3C specification builds on WCAG and adds ebook-specific requirements:
- Discovery metadata, machine-readable declarations of what accessibility features the book includes
- Navigation, a proper table of contents embedded in the EPUB
- Content adaptation, support for text resizing and reflowable layouts
What Makes an EPUB "Accessible"?
Here are the specific elements that retailers and accessibility checkers look for:
1. Accessibility Metadata
Your EPUB's content.opf file should declare its accessibility features. This includes properties like:
accessibilitySummary, a human-readable description of the book's accessibilityaccessibilityHazard, whether the book contains flashing, motion, or sound hazardsaccessibilityFeature, what features are present (alt text, structural navigation, etc.)accessMode, how the content can be consumed (textual, visual, auditory)
Without these declarations, automated quality checks can't verify your book's accessibility, and may assume the worst.
2. Alt Text for Images
Every meaningful image in your EPUB should have an alt attribute describing its content. This serves two purposes:
- Screen readers announce the description to blind or low-vision readers
- Quality checkers verify that images are properly described
Decorative images (borders, spacers) should have empty alt text (alt="") to tell screen readers to skip them. For a deeper dive into writing effective descriptions, see our complete guide to alt text for ebooks.
3. Heading Hierarchy
Your EPUB's XHTML content should use headings in a logical order: h1 for the title, h2 for chapters or major sections, h3 for subsections, and so on. A common violation is jumping from h2 to h4, skipping h3 entirely.
Broken heading hierarchies make it harder for screen reader users to navigate your book and are flagged by accessibility checkers.
4. Link Contrast
If your ebook contains links (to footnotes, external resources, or internal sections), those links must be visually distinguishable from surrounding text. The WCAG requirement is a 4.5:1 contrast ratio. Many EPUB templates use light blue links on white backgrounds, which often fail this check.
5. Language Declaration
Your EPUB should declare its primary language in the HTML lang attribute. This helps screen readers pronounce words correctly and is required by WCAG.
Why Accessibility Matters for Sales
Beyond the ethical case for making books available to all readers, there are hard business reasons to care about EPUB accessibility:
Amazon's quality system. KDP runs automated accessibility checks on uploaded EPUBs. Books that fail may have their search visibility reduced. This "silent suppression" can tank sales without any notification to the author. We cover the details in our guide to Amazon book suppression.
The European Accessibility Act. Since June 2025, all ebooks sold in the EU must meet accessibility standards. Non-compliant books can be removed from sale in EU markets.
Apple Books and other retailers. Apple has its own accessibility requirements, and other retailers are following Amazon's lead in prioritizing accessible content.
Reader trust. Accessible books receive fewer complaints, fewer returns, and better reviews from readers using assistive technology.
How to Check Your EPUB's Accessibility
The industry-standard tool is DAISY Ace, an open-source checker developed by the DAISY Consortium. It evaluates your EPUB against WCAG 2.1 AA standards and produces a detailed report.
You can run Ace on the command line, or use a web-based tool like Rahatt that wraps Ace in a friendly interface and translates the results into actionable recommendations.
A typical scan takes under 60 seconds and will tell you exactly what needs to be fixed.
Common Misconceptions
"My book is text-only, so accessibility doesn't apply." Even text-only books need metadata, heading structure, and language declarations. These are checked regardless of whether your book contains images.
"My formatter/designer handled this." Many formatting tools don't output fully accessible EPUBs. It's worth scanning the final file regardless of how it was produced.
"I published years ago and it was fine." Standards have tightened significantly. A file that passed in 2020 may fail checks today, especially with the EAA in effect.