What does accessibility mean for PDFs?
An accessible PDF is a document that can also be used by people with disabilities, for example by people who are blind or visually impaired and use screen readers, or by people with motor impairments who cannot use a mouse. Accessibility does not mean the document looks different, it means its structure and metadata are designed so that assistive technologies can work with it.
This may sound like a niche concern, but it is not. In many countries, accessibility is legally required for public sector organizations. And outside the public sector, pressure to make documents accessible is growing steadily.
Technical basics: what makes a PDF accessible?
The following elements are crucial for an accessible PDF:
Tags and logical reading order
Accessible PDFs contain a tag structure that tells the screen reader in what order to read the content and what type of content it is (heading, paragraph, list, table). Without tags, a screen reader reads text in the order it is stored in the document, which often does not match the visual reading order.
Alternative text for images
Images, graphics and diagrams need alternative text (alt text) that describes what the image shows. Only this way can visually impaired people understand the content.
Document language
The language of the document must be defined so that the screen reader sets the pronunciation engine correctly.
Bookmarks and navigation aids
Long documents should contain bookmarks that allow jumping directly to specific sections, similar to a table of contents.
Forms with labels
Form fields in PDFs must be labeled so that assistive technologies can tell the user what to enter in the field.
Accessibility when creating documents
The easiest approach is to consider accessibility when creating a document. In Microsoft Word, accessibility can be checked via the built-in Accessibility Checker before exporting as PDF. When exporting, select the option "Create accessible PDF" or "Tagged PDF".
The same applies to LibreOffice, Adobe InDesign and other programs that support PDF export.
Making existing PDFs accessible
For scanned documents or older PDFs without a tag structure, retrofitting accessibility is more involved. First, the document needs real, searchable text, which requires OCR. With OCR PDF, a scanned document can be converted into a text-based PDF that can then be further processed.
For full accessibility, with tags, alternative texts and correct reading order, Adobe Acrobat Pro or a specialized accessibility tool is usually required. Simple online tools often only offer OCR and basic structuring.
PDF/UA, the standard for accessible PDFs
PDF/UA (Universal Accessibility, ISO 14289) is the international standard for accessible PDFs. A PDF/UA-compliant document meets all technical accessibility requirements. Anyone creating documents for public sector organizations or in regulated industries should aim for PDF/UA compliance.
Related is the PDF/A format, designed for long-term archiving. With PDF to PDF/A, documents can be converted to this archival format, which guarantees long-term readability without software dependencies.
Practical checklist
- Document has a defined language
- All headings are tagged as such (H1, H2, etc.)
- Images have alternative texts
- Tables have header rows
- Form fields have labels
- Bookmarks present for long documents
- Sufficient contrast between text and background (minimum 4.5:1)
- No pure image-text without alternative text
Conclusion
Accessibility in PDFs is not a luxury but a matter of making information available to everyone. Anyone who creates documents with accessibility in mind from the start saves considerable effort afterwards, and reaches users who depend on assistive technologies.