TL;DR: Alt text is essential for making PDFs accessible to visually impaired users and meeting legal standards like WCAG and Section 508 . To write effective alt text, focus on clear, concise descriptions that convey the image’s purpose without redundancy. Skip decorative images and ensure complex visuals have both alt text and detailed explanations.
Why Alt Text is Crucial in PDFs
Images in PDFs often carry essential information—charts, graphs, diagrams, and more. Without alt text, users relying on screen readers are left in the dark.Here’s why alt text is non-negotiable:
- Improves Accessibility
Alt text allows screen readers to describe images to visually impaired users, ensuring everyone receives the same information. - Compliance with Accessibility Standards
Regulations like WCAG and Section 508 require alt text for images in digital documents, including PDFs. - Enhances User Experience
Clear, descriptive alt text makes your content more inclusive and demonstrates a commitment to serving all users.
Best Practices for Writing Alt Text
Writing alt text isn’t difficult, but it does require thoughtfulness to ensure clarity and usefulness. Here’s how to get it right:-
Be Descriptive but Concise
Provide enough detail to convey the image’s purpose without overwhelming the user.
Example: For a bar chart, write, “Bar chart showing annual sales from 2020 to 2025.” -
Focus on the Image’s Purpose
Tailor your description to the specific message the image conveys.
Example: For a product photo, describe its key features instead of unrelated details. - Avoid Redundancy
Don’t repeat information already present in the surrounding text unless it’s critical for understanding. - Skip Decorative Images
Mark purely decorative images as “decorative” or leave their alt text blank to prevent screen readers from wasting time on irrelevant content. - Use Plain Language
Avoid jargon and complex phrases. Write descriptions that are straightforward and easy to understand.
When to Use Alt Text
Not every image in a PDF requires alt text. Here’s how to decide:- Informative Images
Examples: Charts, graphs, diagrams, and product photos.
These images convey important information and must have alt text. - Decorative Images
Examples: Background patterns or aesthetic graphics.
These add visual appeal but no essential information, so they don’t need alt text. - Complex Images
Examples: Infographics, detailed maps, or technical diagrams.
Use a brief alt text and provide more detailed explanations elsewhere in the document.
How to Add Alt Text to PDFs
Adding alt text to PDFs is easy if you use the right tools. Here’s how to do it in Adobe Acrobat Pro:- Open the PDF
Ensure you’re using the Pro version, as the free version doesn’t support adding alt text. - Select the “Edit PDF” Tool
Go to the right-hand menu and click on “Edit PDF.” - Right-Click the Image
Choose “Edit Alt Text” from the context menu. - Enter Your Alt Text
Type a clear and concise description of the image. - Save Your Changes
Make sure to save the document to embed the alt text.
Closing Thoughts: Accessibility is a Must, not a Maybe
Alt text might seem like a small detail, but it’s a game-changer for making PDFs accessible to all users. By writing thoughtful descriptions and applying them effectively, you not only ensure compliance with regulations but also show your commitment to inclusivity.Start implementing alt text today to make your PDFs accessible, compliant, and user-friendly for everyone.
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Last updated . Reviewed by the EqualWeb accessibility team.
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