Evaluating Your EPUB’s Accessibility

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“Just how accessible is our content?” This is a question we often wonder about, but rarely have much time to explore. The documentation is technical, the considerations are broad, and everyone seems to have a different idea of how it’s done. The truth is, producing accessible material is easier than most people think, and checking it is even more straightforward.

To test an EPUB:

  1. Load the EPUB file into Bookshelf and Ace (following instructions in this document).
  2. Record a pass or fail for each issue in the sections below.

In the pages to follow, we’ll guide you through some tests you can perform on your files to determine how accessible they are in key areas. This provides a valuable benchmark, but the gold standard is still an experiential evaluation performed by a reader who uses assistive technology every day. For a full picture of a file’s accessibility, consider hiring a trained accessibility tester to review the publication for you.

Table of Contents

Setting Up

In order to get accurate results, we’re going to set up a quick testing environment. These tools of the trade will tell us what is done right … and help to pinpoint areas of concern.

Ace Report

The most robust accessibility checker is called Ace. It’s produced by the DAISY Consortium, and is available free of charge. Ace for Desktop is available for Windows, Mac, or Linux. We recommend the desktop version, because it’s so easy to use. Just drag and drop the book onto Ace, and in a few seconds, it will have a report ready for you. Don’t worry, finishing the Ace check is more than enough for now. We’ll go through the report together in a moment.

Smart-Phones and Tablets

Did you know that mobile phones and tablets have assistive technology built right into them? You can make your phone announce whatever comes up on the screen right out of the box, without installing anything. We’ll show you how to do that in a moment.

For now, we recommend installing Bookshelf from Vital Source. This E-reader is completely free, and offers a stable, reliable interface. We selected this particular app because it’s available on iOS and Android, has a read-aloud feature, and does a good job of correctly identifying different parts of the book. Unless you are confident in your awareness of how screen readers interact with various elements, using a different reading system for these tests could seriously skew your results.

Once your E-reader / reading system is open, go ahead and load the book we’re testing into it. You can browse for it on your device’s built-in storage, or export it right from your Dropbox. For more detailed instructions on opening a book with Bookshelf, check out VitalSource’s page on Sideloading EPUBs with Bookshelf (with instructions for macOS, Windows, Android, and iOS.)

We will need to enable a screen reader in order to complete some of our tests.

  • If you’re using an iOS device, tap Settings, then General, then Accessibility. Select VoiceOver, and turn the toggle switch on. (You can also ask Siri to turn VoiceOver On and Off.) You can adjust the speaking rate in the screen in the settings.
    The VoiceOver pause and resume shortcut (triple-tap Home button) is enabled by default. For more information on doing accessibility testing using VoiceOver (including a list of gestures for all core functions) we recommend this guide from WebAIM: Using VoiceOver to Evaluate Web Accessibility. For additional reference, see this complete list of VoiceOver gestures from Apple.
  • If you’re on Android, tap Settings, then Accessibility. Select TalkBack, and turn the switch on. You can adjust the speaking rate by pressing Settings. The TalkBack Suspend and Resume Shortcut (long-press volume buttons) can also be enabled here. For more information on doing accessibility testing using TalkBack (including a list of gestures for all core functions) we recommend this Android Accessibility guide from Google Support: Use TalkBack Gestures.

Caution: because these accessibility features allow touch-screen exploration, your device will behave differently when they are enabled. For instance, you will need to double-tap items to activate them, instead of the single-tap you’re used to. The shortcut to turn the feature on and off (on iOS devices) is therefore quite helpful.

Testing the Title

Over the next few minutes, we’ll guide you through an accessibility tour of the book you’ve selected. Sit back and decide for yourself whether you’re happy with how this ebook behaves with assistive technology. Let’s dive in!

Fixed Layout

Pre-paginated books present many challenges to assistive technology. The most obvious of these is the choppy reading experience, as demonstrated in this NNELS video: Fixed Layout vs. Reflowable EPUBs.

If you have the book open in your reading system, go ahead and press Listen. Titles produced in a fixed-layout style are usually read one word at a time. If the text is narrated smoothly, the test passes.


Describe Images

Accessibility guidelines state that all content in your book should be available to eyes, ears and fingers. That means describing the visual elements of an image, so everyone can understand it. For detailed information about image description, check out NNELS’ Image Description Guide.

To get an idea of how this works with assistive technology, let’s turn to your reading system. Find a page in your book that contains an image, and tap the Listen button. When narration arrives at the image, it will speak the alternative text that was provided for it. If you just hear the filename of the JPEG, this test fails. This is not very helpful, as it does not describe the image. You will notice the difference when the image has useful alt text and in this case, of course the test passes.

Ace has a whole tab set aside for images in your book, so you can assess the quality of your descriptions all in one place. Just select the Images tab, and take a look at the table below. The column called Altattribute shows the image descriptions in your content that are currently being offered to screen readers.

A quality image description will:

  1. Present new information that does not appear in the text around it.
  2. Employ a writing style in line with the narrative.
  3. Convey all important visual elements.

Ignore Decorative Images

Decorative images should not be described. In fact, images that exist solely to enhance the layout of the page should be set up to be ignored by assistive technology, so they don’t disrupt the main narrative. Let’s give this a try in your reading system too. If you can find a page in your book that has a graphic solely for presentation, go ahead and listen to the text around it. If the narration ignores the image, that’s a really good sign.

For a more systematic analysis of decorative images, Ace also comes in really handy. This time, have a look at the Role column. The Role attribute indicates to assistive technology what role the image plays in the book. If decorative images are set to “presentation” here, this test passes.

Note that EPUB 2 doesn’t support this feature. So, if you’re testing a version 2 EPUB, just ensure the altattribute of decorative images is empty; the role need not be set to “presentation”.


Headings give structure and navigation to your content. Without them, assistive technology just sees a wall of text. And while your headings may look fine visually, screen readers may not be able to understand them as structural elements unless they are properly formatted.

Identify Sections

Every section in your book should start with a heading. This includes parts and chapters, as well as front and back matter. When you look at the book in your reading system, it probably appears as if this has been done well. But let’s quickly make sure a screen reader can actually pick up on your headings.

Flip to the start of a section in Bookshelf, turn on your screen reader, and tap a heading. The section title should be announced, followed by “Heading Level 1.” This will give you an idea of how well assistive technology understands your content.

Select the Outlines tab on the Ace report, and scroll down to the Headings outline section. If every section is listed here, this test passes.

Cascade Headings

Headings are like the descendants on a family tree. The first level should be reserved for the most important sections, and the second level is for children of the parent section. In fact, complex content can utilize up to six heading levels.

Jonathan Swift’s famous work, Gulliver’s Travels, contains four parts, under which are several chapters. So we would set each part up as a level one heading, and each chapter as a level two heading. Note: Top level content like Title Page, Copyright, Dedication, etc. should also have level one headings.

With this in mind, let’s take a closer look at the Headings outline on the Ace report. Note that each line in the list begins with a heading number, such as h1. In order for this test to pass, major sections must be denoted with h1, child sections with h2, subsections with h3, and so on.

Combine Headings

Next, we want to make sure that each section is indicated with only one heading. The first part of Gulliver’s Travels is called “A Voyage to Lilliput”. The first heading of the narrative, therefore, should be “Part One: A Voyage to Lilliput”. “Part One” and “A Voyage to Lilliput” should never be set up as separate headings, since both phrases encompass a single title. Repetitive headings are confusing to readers who navigate your book by headings.

Let’s take another quick glance through the Ace report’s Headings outline. This time, be on the lookout for chapter numbers and titles that appear in separate headings. If you don’t find any, this test passes.

Style Text

The last thing to check is that all headings denote a new section. Headings should never be used just to make text larger. We don’t want to see, for example, headings used on the title page, just to make a name or date stand out.

Let’s take one final pass through the Headings outline on the Ace report. If you don’t see any headings employed just for style, this test passes also.

Table of Contents

If you want to read chapter twelve of your favorite book, you’ll probably turn to the table of contents to find out where it begins. The Contents page ensures that you can always find the section you’re looking for. In fact, the Table of Contents feature is so important to EPUB publications that they usually have two of them. The Contents page is used by readers, typically found in the front matter of the text. And the Navigation Pane is found in your reading system, built from a special machine-readable file within the book’s code.

The Navigation Pane

The navigation pane is the most efficient way to navigate a book, so it’s important that all sections are referenced here. Simply pull up the navigation pane in your reading system, and check through the list that appears. If every section – including front and back matter – is listed, this test passes.

The Contents Page

The most useful contents pages link to sections throughout the book. That way, when a reader comes across a section they want to read, they can simply click on its title to start reading. “A best practice for Tables of Contents is to present the section links as a list, so assistive technology can announce how many items are available.

Open your book in Bookshelf, and turn to the contents page. Now, let’s take it for a test-drive with a screen reader. Activate speech feedback with the gesture we discussed earlier, and tap the last item on the page.

First, you should hear the name of the section being announced. The word “Link” should then be spoken, to indicate the item can be easily selected and activated. Finally, you should hear something about a list, to confirm the items in this section are classed as a structured list. VoiceOver will say “List end,” and TalkBack should say something like “In list, 13 items.” If you cannot click links, or of items are not in a list (in cases with many sections in the table of contents) this test fails.

Footnotes and Endnotes

If your content includes footnotes or endnotes, it’s important to connect them to the text with a network of links. That way, it’s easy to find the note, read it, then return to the main narrative.

Let’s give this a try in your reading system. Turn to a page that contains a note, and tap its number. This should activate a link that takes you to the note you selected. But once you’ve finished reading the note, you should find a “Return to Text” link that returns you to your original place in the book. If both these links work, this test passes.

Title Page

The title page is the first thing your readers will find when they open your book. Too often, however, this important page is set as an image. This is not helpful for readers with print disabilities, as assistive technology cannot read images.

To test for this, simply turn to your title page in Bookshelf, and press Listen. As long as the title, author, and other information on this page is spoken, this test passes.


If your book contains tables, we want to make sure they will make sense to readers who cannot see them.

Setting them up in text is the first major step, so if you find one that’s set as an image, this test fails. Beyond that, tables need to include headings, so screen readers know what information is being conveyed in each column.

Let’s check this out in your reading system. Flip to a table in your book, turn the screen reader on, and tap a cell in the table.

You should hear the title of the column, followed by the text in the cell. An announcement will usually follow to give the cell’s position in the table. For example, feedback of “City, Vancouver, row 1 column 1” is typical. If you don’t hear the column’s title, the headings in your table are likely not set up properly.


Link Captions

Captioning links is important for all readers, not just those using assistive technology. A caption tells users where a link will take them if they click it, and neglecting a link caption will generate a serious violation on the ACE report, with the notation “Element is in tab order and does not have accessible text“.

Once you ensure all the links in your book are captioned, review the links within the text itself to make sure that their caption text is useful. Link text is usually underlined and shown in a different color. When you find a link, just read its text with the screen reader, without looking at the surrounding narrative. Screen reader users often jump directly to a link with a shortcut key or gesture. They rely on the caption to decide whether or not to click on it, so captions that simply say “Here” or “Go” aren’t very helpful. As long as the caption makes sense on its own (such as “Visit the Author’s Home Page” or “Click here for Further Resources”), this test passes.

Active URLs

Copying text out of an ebook and into your smart-phone’s address bar is somewhat difficult with a screen reader. That’s why we recommend that any URLs in your book be set up as active links that readers can tap on to visit the web page.

This test is easy. When you come across web addresses in your book, ensure they are set up to open the website when clicked.


For many years, publishers have been making the first letter of a chapter larger than the surrounding text. This adds character and appeal to the book, while setting the start of chapters apart from the rest of the narrative. However, unless carefully handled, dropcaps can really disrupt the reading experience.

If your book contains dropcaps, navigate to the start of a chapter in your reading system, and press Listen. Often, the first letter will be read separately (something like “T. he dog looked up.”). If the first sentence is read properly, this test passes.

Uppercase Words

Assistive technology doesn’t cope well with uppercase words. Small words are thought to be acronyms, titles like Mr. and Mrs. are mispronounced, and the word “A” is given undue emphasis. For this reason, title case is recommended for headings, and lowercase text is preferred for the main narrative. The practice of typing titles (and often the first few words of each chapter) in uppercase letters is strongly discouraged.

The test for capitalization doesn’t even require a screen reader, unless you want to hear what this text sounds like. Just flip to the first page of the book in your reading system, and make sure you don’t see uppercase words. If only the first letter of words are capitalized, this test passes.

Semantic Structure

Throughout a book, visual clues are used to set various elements apart from the rest of the text. Horizontal lines separate small sections, sidebars provide anecdotal information, block-quotes are indented, and captions appear directly below important figures. Readers who cannot see these visual clues, however, rely on their screen reader to indicate different elements. If a sound semantic structure is used throughout the book, they can provide this feedback in the form of audible warnings.

To test this, when you have the EPUB file open in Bookshelf, tapping a horizontal line should cause your screen reader to announce “Separator.” If you encounter a sidebar, your screen-reader should read its text, followed by the word “Complementary.” And touching an image will cause its alternative text to be spoken. If your book has any of these elements and they are well-described by the screen reader, this test passes.

Accessibility Metadata in the EPUB

Extended metadata tags can be used to outline how accessible your book is. These allow producers to specify how the content can be read, indicate what features are available, and summarize the overall accessibility of the publication. If you can assure readers with print disabilities that they will have full access to the content, you can broaden your market and make everyone feel included. If this is not the case, however, you can avoid disappointment by noting the specifications that it does meet in the metadata as well.

Yet again, the Ace tool is our friend for this test. First check the Violations tab, as neglected accessibility metadata will generate warnings. If everything looks good, select the Metadata tab just to make sure the statements made about this book’s accessibility are accurate.

In the ONIX Record

Readers with print disabilities need to know before purchase – and even before publication – whether a particular ebook will meet their needs. However, books protected with DRM cannot expose this valuable information to search engines. For this reason, in addition to the accessibility metadata inserted in the EPUB itself, similar data can also be added to the book’s ONIX record. When distributed within the standard ONIX metadata, data aggregators, libraries and retailers can be aware of the level of accessibility of a particular ebook before the title itself is available, and can present this information to potential purchasers and readers within their catalogue. It’s another great way to advertise a book’s accessibility – while promoting it to a wider audience in the process.


A handful of modern EPUBs contain multi-media within their pages. Going well beyond traditional photos and images, it is possible to include audio or video presentations alongside the text in your ebooks. This is a great way to engage readers in your publication, but it’s important to ensure that all readers can benefit from this special content.

Here are two things to test.

  1. First, if your book contains audio narration, make sure the text aligns with the spoken narration. As each sentence of the audiobook is read, the same text should be highlighted on screen.
  2. Next, if your publication contains videos, ensure they are described with a separate audio track or accessible text portion.

Final Thoughts

There are some additional features that are important for accessibility and usability that are not included in this guide. The features above are easier to check for someone new to how screen readers function. While the issues above are not exhaustive, they will give you a very good idea of how accessible your files really are for someone using a screen reader.

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