Adobe’s Portable Document Format (PDF) is a popular option for presenting and sharing electronic documents. Unfortunately, while the format is robust enough to maintain presentation on different operating systems, PDFs can have accessibility barriers that affect users with disabilities.
Below, we’ll explain why PDF accessibility should be a priority — and identify some of the common mistakes that make web documents less useful for some readers.
Why is PDF accessibility important?
All of your business’s digital resources need to be accessible, and that includes PDFs and other web documents.
For most organizations, this isn’t optional. The Americans with Disabilities Act (ADA) and other non-discrimination laws require businesses to provide equivalent access for people with vision disabilities, cognitive differences, mobility impairments, and other conditions.
And while compliance is an important consideration, it’s not the only concern: By taking an inclusive approach, your brand shows that it values its customers' experiences. The business case for accessibility is strong, and creating accessible PDFs can help you improve engagement, retain customers, and even enhance your search engine optimization (SEO) efforts.
Technical Standards for PDF Accessibility
To take the first steps, you’ll need to test your content against common technical standards. For PDFs, two standards are cited frequently:
- The Web Content Accessibility Guidelines (WCAG), considered the international standards for digital accessibility. WCAG is also applicable to websites, mobile apps, and other online content.
- The International Standards Organization (ISO) requirements for electronic document file format enhancement for accessibility, PDF/UA (ISO 14289-1:2014).
The ISO’s guide is based on WCAG 2.0. Therefore, some authors reference the ISO standards, while others directly reference WCAG, but both documents have similar requirements.
By following WCAG you can make PDFs more accessible for people who use screen readers and other assistive technologies (AT). The guidelines also include accommodations for people who might not use AT — individuals with low vision, color vision deficiency (CVD), neurocognitive differences, and other conditions.
Below, we’ve detailed some of the most common accessibility barriers that violate WCAG. To fully evaluate your PDFs for accessibility, send us a message or read about our PDF & Document Accessibility Remediation services.
1. Failing to Tag Your PDFs
Websites use HTML (HyperText Markup Language) to structure web pages and their content. Providing a semantic structure ensures that different user agents (such as web browsers or screen readers) can present the content in a way that makes sense.
PDFs also need semantic structure to meet WCAG Success Criterion (SC) 1.3.1, “Info and Relationships.” Of course, PDFs aren’t written with HTML — instead, they use tagging to make sure that content can be accessed with different types of tools.
In simple terms, tags show the structure of your PDF. You can add tags automatically or manually by using Adobe Acrobat Pro and other authoring software.
Adobe provides a guide for using its Reading Order feature, which walks authors through the tagging process. Some quick tips:
- When auto-tagging documents, review the results. No automated accessibility tool is 100% perfect, so make sure that your tags are accurate.
- Don’t add watermarks or other non-essential elements to the tag tree.
- Long PDFs can be made more accessible by adding meaningful bookmarks. These should link to chapters, headings, or other important sections of the document.
For a more detailed explanation of PDF tagging, read Adobe’s Creating Accessible PDFs in Adobe Acrobat guide.
2. Missing Alternative Text
Some users cannot perceive content visually. Alternative text (also called alt text) provides a description of visual content — graphs, photos, and other images — enabling screen readers to describe those components to users.
Quick tips to keep in mind:
- Keep your alt text simple, concise, and accurate.
- Don’t describe non-essential images (such as borders and other decorative elements). Identify these images as “artifacts" to hide them from the accessibility tree.
- If an image contains text, make sure that the alt description includes that text.
- Don’t use phrases like “image of" or “picture of" in your alt text. Screen readers will inform users that they’re focusing on an image, so these descriptions are redundant.
For more guidance, read: What is the Best Way to Write Alternative Text?
3. Ignoring Color Contrast
People with color vision deficiencies (CVD) and other vision disabilities may have trouble reading text that has insufficient contrast with its background. WCAG SC 1.4.3, “Contrast (Minimum)” requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large-scale text.
When designing your documents, test your color-pairs to make sure that they meet these requirements. The Bureau of Internet Accessibility’s Color Contrast Accessibility Validator is a free tool that allows you to check colors instantly.
4. Image-Only PDFs
For many AT users, image-only PDFs are completely unusable — which can be especially frustrating if the document contains content that isn’t available elsewhere.
Adobe’s optical character recognition (OCR) allows authors to automatically convert image-based PDFs to text PDFs. This makes the PDF readable for screen readers (and searchable for all users). Adobe offers a guide for using Acrobat’s OCR feature, which also matches fonts to maintain your document’s visual appearance.
When using OCR, make sure you read the output before publishing. While the tool is extremely useful, it’s not perfect, and a quick review will help you avoid embarrassing mistakes.
5. Not Defining the PDF’s Language
Defining the language of your PDFs will enable screen readers to use appropriate pronunciation rules. To define the language:
- Open the document.
- Go to File and select Properties.
- Select the Advanced tab.
- Under Reading Options, use the drop-down field to select the language.
Wherever possible, the best practice is to create unilingual documents. If your document contains text in several languages (for example, an instruction manual written in several languages), consider splitting those sections into separate documents.
6. Inaccessible Forms
If your PDF contains a fillable form, make sure that users can complete the form electronically. This is important even if you don’t have a way to submit the completed form online — some users may want to complete the form, then print it (as opposed to filling out the form fields by hand).
Use the Run Form Field Recognition to make sure that form fields are interactive. Make sure to type accurate descriptions for each form field. This is required by WCAG SC 3.3.2, “Labels or Instructions,” and it ensures that users understand how to input data.
By planning for accessibility, you can create PDFs that work for more users
While we’ve detailed a few of the most common PDF accessibility barriers, this certainly isn’t a comprehensive list. Reviewing WCAG can help you design more inclusive content, and by testing your documents prior to publication, you can enjoy the benefits of accessibility: improved brand sentiment, higher levels of customer engagement, and a wider audience.
For help with document remediation at scale, send us a message to connect with a digital accessibility expert.