How Do I Check If My PDF Is Accessible?

You can check PDF accessibility using built-in tools in Adobe Acrobat, free online checkers, or dedicated validation tools. The most thorough check uses the PDF/UA standard via tools like the Matterhorn Protocol or veraPDF. But the method you choose depends on how many documents you have, how much time you have, and how confident you need to be in the results.

This guide walks through five approaches, from the simplest manual checks to full standards-based validation.

1. Quick Manual Checks (2 Minutes)

Before you open any tool, you can catch the most common accessibility problems yourself. Open your PDF and try these four things:

Can you select the text? Click and drag across a paragraph. If the text highlights, the PDF contains real text. If nothing highlights — or the selection covers the whole page as a single block — the PDF is likely a scanned image with no underlying text layer. A screen reader cannot read image-only PDFs at all.

Is there a document title? In Adobe Acrobat or any PDF reader, check the document properties (usually under File > Properties). Look for a Title field. If it is blank or says something like "Microsoft Word - Document1.docx," the PDF has no meaningful title. Screen readers announce the title when a user opens the file, so a missing or garbled title is a poor first impression.

Do images have alt text? In Acrobat, open the Tags panel (View > Show/Hide > Navigation Panes > Tags). Find an image in the tag tree, right-click, and select Properties. Look for the Alternative Text field. If it is empty, the image is invisible to screen reader users.

Does the Tab key navigate logically? Press Tab repeatedly. In an accessible PDF, focus should move through the document in a logical reading order — left to right, top to bottom, following the visual flow. If focus jumps around unpredictably, the reading order is broken.

These checks take two minutes and catch the most severe issues. But they only scratch the surface.

2. Adobe Acrobat Accessibility Checker (10 Minutes)

If you have Adobe Acrobat Pro, there is a built-in accessibility checker that tests against a broader set of criteria.

How to run it:

1. Open your PDF in Acrobat Pro
2. Go to Tools > Accessibility (or in newer versions, All Tools > Prepare for Accessibility)
3. Click "Accessibility Check" or "Full Check"
4. Leave the default settings and click "Start Checking"

Acrobat will produce a report in the left panel, organised into categories: Document, Page Content, Forms, Tables, Lists, and Headings. Each item shows a pass (green check), fail (red X), or warning (question mark) status.

What it catches: Missing alt text, missing document title, missing language setting, colour contrast issues, empty tags, missing form labels, and some heading structure problems.

What it misses: Acrobat's checker is a reasonable first pass, but it has significant blind spots. It does not thoroughly validate reading order. It does not check whether alt text is actually meaningful (it only checks whether the field exists). It does not validate complex table structures against the PDF/UA standard. And it can report a document as "passed" when serious structural issues remain.

Think of Acrobat's checker as a smoke test, not a certification. A clean Acrobat report is better than nothing, but it does not mean your PDF is fully accessible.

3. Free Online Tools (15 Minutes)

Several free tools provide deeper analysis than Acrobat's built-in checker.

PAC (PDF Accessibility Checker) — Built by the PDF/UA Foundation, PAC is the most widely recommended free tool for PDF accessibility validation. It checks your PDF against the PDF/UA (ISO 14289) standard and the WCAG 2.1 technical requirements. PAC also includes a screen reader preview that shows you exactly how a screen reader would interpret your document — which is often the most revealing test of all. PAC runs on Windows; the newer PAC 2024 version also offers a web-based option.

PAVE (PDF Accessibility Validation Engine) — A web-based tool from a Swiss university research group. Upload your PDF, and PAVE checks it and attempts some automatic fixes. It is useful for quick checks but has file size limitations.

Tingtun PDF Checker — A free online checker from Norway that tests against WCAG criteria. Simple to use — upload and get a report. Like most online tools, it has file size limits and should not be used for confidential documents.

Limitations of online tools: File size restrictions (often 10-50 MB), privacy concerns with uploading sensitive documents to third-party servers, and varying levels of standards coverage. For university content containing student information or unpublished research, uploading to external services may violate data handling policies.

4. Advanced Validation: Matterhorn and veraPDF (30 Minutes)

If you need to know — with confidence — whether a PDF meets the PDF/UA standard, you need tools that validate against the formal specification.

The Matterhorn Protocol is a set of 31 failure conditions published by the PDF Association. Of these, 15 are machine-checkable (a tool can test them automatically) and 16 require human judgment. The machine-checkable conditions cover structure trees, language tags, alt text presence, heading hierarchy, table markup, and role mappings. PAC uses the Matterhorn Protocol as the basis for its checks.

veraPDF is the most comprehensive PDF/UA validator available. It is open-source and checks 108 rules derived from the PDF/UA specification. It catches edge cases that simpler tools miss — incorrect Scope attributes on table headers, invalid role mappings, malformed structure trees, and more. veraPDF is a command-line tool (Java-based), which makes it less approachable for non-technical users, but it is the closest thing to a definitive pass/fail verdict on PDF/UA compliance.

Running both Matterhorn (via PAC) and veraPDF gives you the most complete picture of your PDF's accessibility status. If a document passes both, you can be reasonably confident it meets the technical standard.

But "meets the standard" is not the same as "is accessible." Which brings us to the final method.

5. Screen Reader Testing (The Gold Standard)

Automated tools check whether the right tags exist. Screen reader testing checks whether the document actually works for someone who depends on assistive technology.

Three screen readers are widely used for testing:

NVDA — Free, open-source, runs on Windows. The most commonly recommended screen reader for testing. Download it from nvaccess.org.

VoiceOver — Built into every Mac (and iPhone/iPad). No installation needed. Activate it with Command + F5. If you are on a Mac, you already have a screen reader.

JAWS — The most widely used commercial screen reader ($90/year for a home licence). If your students use JAWS, testing with JAWS gives the most accurate picture of their experience.

What to listen for: Open your PDF in a screen reader and pay attention. Does the screen reader announce the document title? Are headings announced with their level ("Heading level 2: Results")? Can you navigate between headings using keyboard shortcuts? Are images announced with meaningful descriptions? Do tables make sense — can you tell which row and column you are in? Is the reading order logical, or does content jump around?

Screen reader testing takes the most time, but it catches problems that no automated tool can find. An image might have alt text that says "chart" — technically present, so it passes every automated check — but a student who cannot see the chart learns nothing from the word "chart." Only a human listener can catch that.

No Single Tool Catches Everything

Here is the honest truth about PDF accessibility checking: no single method is sufficient on its own.

Manual checks catch the most obvious problems. Acrobat's checker catches some structural issues. PAC and veraPDF validate against formal standards. Screen readers reveal the real-world experience. Each layer catches things the others miss.

The practical approach for most faculty is:

1. Run PAC — it is free, thorough, and takes five minutes
2. Do a quick screen reader test — even two minutes with VoiceOver reveals a lot
3. Fix what you find — or flag it for your accessibility office

If you are responsible for a large number of documents, manual checking does not scale. You need comprehensive automated validation that can process documents in bulk and tell you exactly where the problems are. But even then, automated tools have limits — they find problems better than they fix them, and the quality of automated fixes varies widely.

The question after "is my PDF accessible?" is usually "how do I fix it?" That is the harder problem, and it is where automated remediation becomes valuable — not just telling you what is wrong, but rewriting the document structure to make it right.

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Aelira checks your PDFs against both Matterhorn and veraPDF standards, then fixes the issues it finds — structure tags, reading order, table headers, alt text, and more. Try it free or learn how it works.