Making PDFs Accessible: A Complete Guide

Accessible PDFs ensure everyone can read and interact with your documents, regardless of disability. Understanding accessibility requirements and implementing best practices isn't just good ethics—it's often legally required and always expands your audience.

Why PDF Accessibility Matters

Approximately 15% of the world's population lives with some form of disability. Vision impairments affect millions who rely on screen readers to convert text to speech or Braille. Motor disabilities make precise mouse control difficult, requiring keyboard navigation. Cognitive disabilities benefit from clear structure and simple language. Learning disabilities are assisted by proper document organization and alternative formats. Color blindness affects how people perceive color-coded information. Creating accessible PDFs ensures your content reaches this significant portion of your audience rather than excluding them entirely.

Legal and Compliance Requirements

Many jurisdictions legally require digital accessibility. In the United States, Section 508 mandates accessibility for federal government documents. The Americans with Disabilities Act (ADA) increasingly applies to digital content. The Web Content Accessibility Guidelines (WCAG) 2.1 Level AA is the international standard most organizations follow. Educational institutions must comply with accessibility requirements under federal law. Government contractors face specific accessibility requirements in their deliverables. Beyond legal obligations, accessibility demonstrates organizational commitment to inclusion and expands your potential audience significantly.

Understanding PDF Accessibility Standards

PDF/UA (Universal Accessibility)

PDF/UA is the ISO standard specifically for accessible PDFs. It defines technical requirements for PDF documents to be reliably interpreted by assistive technologies. PDF/UA compliance ensures documents have proper structure tags defining headings, paragraphs, lists, and tables. All content must be included in either the document structure or marked as artifacts. Alternative text must describe all meaningful images. Document language must be specified for proper pronunciation by screen readers. Color cannot be the only means of conveying information. These requirements ensure assistive technologies can present content meaningfully to users.

WCAG 2.1 Guidelines

WCAG provides broader web accessibility principles applicable to PDFs. Level A represents minimum accessibility (basic requirements). Level AA is the standard most organizations target and what many laws reference. Level AAA represents enhanced accessibility for specialized needs. Key principles include perceivability (information must be presentable to users in ways they can perceive), operability (interface components and navigation must be operable), understandability (information and operation must be understandable), and robustness (content must work with current and future technologies including assistive tools).

Creating Accessible PDFs

Starting with Accessible Source Documents

Accessibility begins before PDF creation. Use proper heading styles (Heading 1, Heading 2, etc.) in your word processor rather than just making text larger and bold. Structure lists using proper bullet or numbered list formatting, not manual symbols. Create tables using table tools, not tabs or spaces for alignment. Add alternative text to images describing their content and purpose. Use built-in caption and label features for figures and tables. Define document language in the source file properties. Well-structured source documents convert to PDFs that are mostly accessible already, requiring only minor adjustments rather than complete remediation.

Document Structure Tags

Tagged PDFs contain structural information that assistive technologies interpret. Heading tags (H1 through H6) create document hierarchy and navigation. Paragraph tags (P) define body text blocks. List tags (L, LI, Lbl) structure bullet and numbered lists properly. Table tags (Table, TR, TH, TD) define table structure and relationships. Figure tags identify images and graphics. Artifact tags mark decorative elements that should be ignored by screen readers. Without proper tagging, PDFs appear as random text blocks to screen readers, losing all organizational structure and making navigation impossible.

Reading Order

Reading order determines the sequence screen readers present content. Logical reading order follows how sighted users would read the document—typically top to bottom, left to right in Western languages. Complex layouts with columns, sidebars, and text boxes can create confusing reading order if not properly structured. Test reading order by using a screen reader or tab through the document—content should flow logically. Incorrect reading order makes documents incomprehensible to screen reader users, even if all other accessibility features are correct. Many PDF authoring tools allow adjusting reading order after creation.

Alternative Text and Descriptions

Writing Effective Alt Text

Alternative text describes images for people who cannot see them. Good alt text is concise but descriptive, typically under 125 characters for simple descriptions. Describe the image's content and purpose, not just what it shows—context matters. For decorative images that convey no information, mark them as artifacts or use empty alt text so screen readers skip them. For complex images like charts or diagrams, provide both brief alt text and longer descriptions. Don't start with "Image of" or "Picture of"—screen readers already announce it's an image. Focus on information the image conveys, not exhaustive visual details.

Complex Graphics and Charts

Graphs, charts, and technical diagrams require more detailed descriptions than simple images. Provide a brief alt text summary of the graphic's purpose and main finding. Include a longer description nearby in the document text that explains data trends, important values, and relationships shown. For data charts, consider including the underlying data in a table as well as the graphic visualization. Technical diagrams may need detailed text explanations of components and their relationships. The goal is conveying the same information visually-impaired users need without forcing them to see the graphic itself.

Color and Contrast

Contrast Requirements

Sufficient color contrast ensures text remains readable for people with low vision or color blindness. WCAG requires a 4.5:1 contrast ratio for normal text (under 18pt) and 3:1 for large text (18pt and larger or 14pt bold). These ratios measure the difference between text and background colors. Use online contrast checkers to verify your color combinations meet requirements. Light gray text on white backgrounds frequently fails contrast requirements. Very dark backgrounds with colored text can also fail. High contrast benefits everyone, especially in poor lighting conditions or on low-quality displays.

Color as Information

Never use color alone to convey information. Color-blind users cannot distinguish certain color combinations. Screen readers don't announce colors to users. If your document uses red for negative numbers and black for positive, also include minus signs or parentheses. Charts using only color to distinguish data series should also use different line styles or markers. Important warnings shouldn't rely solely on red text—use icons, bold text, or other visual indicators as well. This principle ensures information remains accessible regardless of how users perceive color.

Tables and Forms

Accessible Table Design

Tables require special attention for accessibility. Use proper table tags with designated header rows or columns. Associate header cells with their data cells using scope or ID attributes. Avoid merged cells and complex nested tables when possible—they confuse screen readers. Provide table captions or summaries explaining the table's purpose. Keep tables simple and focused on a single data set rather than complex multi-part tables. For financial or statistical tables, ensure screen readers can navigate and understand relationships between cells. Consider whether information could be presented more accessibly in a different format.

Form Accessibility

Interactive PDF forms must be accessible for keyboard-only users and screen reader users. Every form field needs a clear, descriptive label properly associated with the field. Provide tooltips with additional instructions for complex fields. Ensure logical tab order through form fields. Group related fields using fieldsets with legends. Mark required fields clearly, not just with color or asterisks. Provide clear error messages that identify which fields have problems and how to fix them. Test forms with keyboard-only navigation—users should be able to complete and submit without using a mouse.

Navigation and Interactive Elements

Bookmarks and Document Outline

Bookmarks (also called document outline) provide navigation shortcuts, especially valuable for long documents. Create bookmarks from heading structure to mirror document organization. Ensure bookmark labels are descriptive and match actual headings. Nested bookmarks should reflect heading hierarchy (H1, H2, H3 structure). For documents over 10 pages, bookmarks are essential accessibility features, not optional enhancements. Screen reader users rely on bookmarks to navigate efficiently rather than listening to entire documents sequentially.

Hyperlinks

Links must be accessible and understandable out of context. Use descriptive link text that makes sense when read alone—avoid "click here" or "read more." Link text should indicate the destination or action clearly. Ensure links have sufficient color contrast and aren't indicated by color alone—underlines help. Test that links are keyboard accessible. For external links, consider indicating they leave the document. Make sure link purposes are clear from their text, not just from surrounding context, since screen readers often list links separately from document flow.

Language and Text

Document Language

Specify the document's primary language so screen readers pronounce text correctly. English text read with Spanish pronunciation rules sounds incomprehensible. For multilingual documents, mark sections in different languages with appropriate language tags. This allows screen readers to switch pronunciation rules automatically. Without language specification, screen readers guess, often incorrectly. Language tags are especially critical for proper names, technical terms, and any non-primary language content.

Clear and Simple Language

While not strictly a technical requirement, clear language improves accessibility for people with cognitive disabilities and non-native speakers. Use short sentences and simple sentence structure. Define technical terms and acronyms on first use. Use common words rather than jargon where possible. Break complex information into shorter sections with clear headings. Use bullet points for lists rather than long paragraphs. Provide summaries of complex information. These practices benefit all readers while being essential for some.

Testing PDF Accessibility

Automated Checking Tools

Automated tools identify many accessibility issues quickly. Adobe Acrobat's built-in accessibility checker finds common problems like missing tags, missing alt text, insufficient contrast, and improper reading order. PAC (PDF Accessibility Checker) is a free tool specifically for PDF/UA validation. Online validators can check PDFs for WCAG compliance. However, automated tools catch only about 30-50% of accessibility issues. They identify technical problems but can't judge if alt text is meaningful or reading order makes sense. Use automated checking as the first step, not the final verification.

Manual Testing Procedures

Human testing catches issues automated tools miss. Navigate the entire document using only keyboard (no mouse) to verify all content is accessible. Use a screen reader (NVDA and JAWS on Windows, VoiceOver on Mac) to experience how the document sounds. Verify reading order makes sense by listening to the document. Check that all images have meaningful alt text or are marked as decorative appropriately. Confirm tables can be understood without seeing them visually. Test forms for keyboard accessibility and clear error messages. This testing reveals usability problems that technical validation misses.

User Testing

The ultimate test is having people with disabilities try to use your document. If possible, work with users who rely on assistive technology daily. They identify real-world problems that both automated tools and inexperienced manual testing miss. User testing reveals whether your document is technically compliant but still difficult to use. Observe where users struggle, get confused, or cannot complete tasks. This feedback is invaluable for improving not just one document but your entire accessibility process.

Remediating Inaccessible PDFs

When Remediation is Needed

Legacy documents and PDFs from external sources often lack accessibility. Scanned documents without OCR have no text layer at all. Documents created from poorly structured source files inherit those problems. Auto-generated PDFs from web pages or databases may lack proper tagging. Historical archives may predate accessibility awareness. Remediation adds accessibility features to existing PDFs rather than recreating from source.

Remediation Process

Systematic remediation produces better results than ad-hoc fixes. Run OCR on scanned documents to create searchable text. Add or verify document tags for proper structure. Set correct reading order throughout the document. Add alternative text to all meaningful images. Mark decorative elements as artifacts. Define table structures and headers. Add bookmarks for navigation. Specify document language. Fix color contrast issues. Test thoroughly with accessibility tools and screen readers. Document-by-document remediation is time-consuming, but essential for providing equal access to existing content.

Maintaining Accessibility

Accessibility Workflows

Building accessibility into your document creation process ensures consistent results. Train all document creators on accessibility basics. Use accessible templates with proper styles and structure. Include accessibility checking in your quality assurance process. Assign responsibility for accessibility verification before publishing. Document your accessibility standards and procedures. Review and update processes as standards evolve. Making accessibility routine rather than an afterthought produces better documents with less remediation effort.

Ongoing Improvement

Accessibility is a journey, not a destination. Stay current with evolving standards and best practices. Learn from user feedback about accessibility problems. Continuously improve templates and processes based on what works well. Invest in training as new team members join. Update legacy documents as they're revised rather than all at once. Share knowledge across your organization. Each document you make accessible helps users immediately and improves your skills for future documents.

Conclusion

PDF accessibility ensures your documents reach everyone, regardless of disability. While creating truly accessible PDFs requires attention to structure, tags, alternative text, and navigation, the effort expands your audience and often fulfills legal requirements. Start with accessible source documents, use proper tagging and structure, provide meaningful alternative text, and test with both automated tools and real users. Whether creating new documents or remediating existing ones, following accessibility best practices demonstrates commitment to inclusion and ensures your information is truly available to all.

Related tools: Extract Text, Edit Metadata, Add Page Numbers, Headers & Footers