Alternative Text (Alt Text) for your Figures

What Is Alt Text?

Alternative text (also called alt text) is short meaningful text describing the contextually relevant aspects/elements of an image/graphic. In short, this text represents the image itself. Alt text should be 2–3 meaningful sentences. On average, alt text should be ~125 characters, but no more than 250 characters.

Why Is Alt Text Important?

Alt text is an important part of digital accessibility. It serves as the text equivalent of an image/graphic. Alt text helps individuals with a visual disability or impairment or processing disorder who use assistive technology to access data. Types of assistive technologies include: screen readers, Braille displays, and audio/text-to-speech technology. It is important that all users have an inclusive equivalent experience with digital content.

The GAAD Foundation states: 1 billion people worldwide have disabilities (https://accessibility.day/). This is a significant portion of the population.

There are laws, standards, and guidelines in place to aid those with disabilities.

  • Web Content Accessibility Guidelines (WCAG) standards ensure those who have disabilities and/or use assistive technology can use electronic materials and websites. WCAG success criterion 1.1 on non-text content compliance requires that all non-text content have a text alternative that serves the equivalent purpose of the image. Note: Alt text is a minimum accessibility requirement and you cannot reach any WCAG conformance level (A, AA, AAA) without it.
  • Alt text for your book figures is necessary for European Accessibility Act compliance.

Writing Alt Text

When writing alt text for your figures, consider (and keep in mind) the following:

  • Be concise. Assistive technology cannot pause alt text.
  • The reason you are providing the figure/image/graphic. What is its purpose and intent for the reader?
  • Consider word choice and use.
  • Consider your audience and the user experience. It is important not to simply repeat the caption. The reader will have access to the caption. Figure captions and alt text serve different purposes.
  • Eliminate redundancy. Repetition can be cumbersome for a reader using assistive technology.
  • Please do not state “image” or “photo” at the start of an alt text description, assistive technology will state this. However, if it is a map, chart, or graph, state this at the start so the audience can prepare for the description that follows.
  • AI (artificial intelligence) can be helpful to use as a starting point when learning to write alt text, but check that its description is accurate.
  • Read aloud your final alt text to imagine how a screen reader will sound to a reader when the alt text is read. Or better yet, try using an actual screen reader.
  • Alt text should be an integral part of your manuscript workflow and included early in the process with your final manuscript.

The alt text for a figure should be placed at the end of your manuscript following its figure caption. This way, you can be sure you aren’t simply repeating what is already there. Start the alt text with an indicator note such as “[[Figure 1 alt text]],” so the editors will know immediately what it is.

Keep in Mind

Alt text should be brief, meaningful, and contextually relevant–Consider the audience that needs it. Writing alt text will get easier with practice. Accept the challenge and give it a try for your figures. After all, you know your science best!

Resources

Americans with Disabilities Act (ADA)
World Wide Web Consortium (W3C)
Web Accessibility in Mind
European Accessibility Act