When companies come to us with their PDFs, many have already checked them themselves. That’s good, because if you check them, you know where you stand. The real surprise usually comes elsewhere: in the number of documents and in an error that hardly anyone expects.
In this guide, I’ll show you how to check a PDF for accessibility, which tools are best suited for the task, which errors crop up most frequently in practice, and how to integrate this checking process into your workflows so that it doesn’t turn into a major project. I explain how to create an accessible PDF from the outset in the guide ‘Creating an accessible PDF’. This guide focuses solely on checking.
In a nutshell: checking a PDF for accessibility in six steps
- Compile an inventory: all PDFs on the website and the number of pages per document.
- Check automatically, for example using Access Read, PAC or Adobe Acrobat Pro.
- Sort the results: technical errors on the one hand, and issues requiring human assessment on the other.
- Check tables, reading order and alternative text specifically, ideally using a screen reader.
- Make documents with errors accessible or correct them in the source file.
- Make the check a fixed part of the process before a new PDF goes live.
What makes a PDF accessible
An accessible PDF contains a structure behind the visible page, known as tags. These tell a screen reader what constitutes a heading, a list or a table, and in what order the content should be read. In addition, there are alternative texts for images, a specified document language and a meaningful title. The relevant standard is PDF/UA, the international standard ISO 14289.
If this structure is missing, the PDF looks completely normal to sighted people. However, a screen reader will then, at best, read out unordered text and, at worst, nothing at all – for example, in the case of a scanned document consisting solely of images.
It is also important to note the difference between ‘low-barrier’ and ‘accessible’ here. Automated processing removes barriers and produces a ‘low-barrier’ PDF. A document is only considered ‘accessible’ once it has been additionally checked by a person. You can read more about this in the guide ‘Creating Accessible Documents’.
What companies use to check PDFs
Most clients who come to us with PDFs that have already been checked have used PAC, the PDF Accessibility Checker. PAC is free, is now provided by axes4, and checks against PDF/UA and the WCAG. To be honest, it’s a good tool, and in practice it doesn’t overlook anything that can be checked automatically. Some clients also use Adobe Acrobat, the Pro version of which includes its own accessibility checker.
With Access Read, we have created a third option: the check is carried out entirely online in your browser. You don’t need to install anything; simply upload your PDF and get the result in seconds, from any computer.
| Tool | Where it works | Strengths | Limitations |
|---|---|---|---|
| PAC (axes4) | Downloadable programme | Free, checks PDF/UA and WCAG, with preview for screen readers | Must be installed |
| Adobe Acrobat Pro | Paid desktop software | Validation right where many PDFs are edited | Licence required; the free Reader version is not sufficient |
| Access Read | In the browser | No installation required, fast, accessible from anywhere | Like any automated check, it is no substitute for human judgement |
What an automated check detects and what it does not
Automated tools can reliably detect whether tags are present, whether images have alternative text, whether language and titles have been set, and whether the structure is formally correct. What they cannot assess is the meaning: whether an alternative text actually explains the diagram, whether the reading order is logical, or whether a heading is, in terms of content, actually a heading.
Practical tip: After the automated check, open a random selection of your most important documents using a screen reader, such as NVDA on Windows or VoiceOver on a Mac. Just five minutes will show whether a document is truly accessible.
The most common error: tables
If I had to say which error crops up most frequently in Access Read, I’d have to say, quite honestly, tables. They’re tricky and never fail to catch people out – even teams that usually do a thorough job.
The reason: sighted people can take in a table at a glance. A screen reader reads it cell by cell. For a number to make sense, the screen reader needs to know, for every cell, which column and which row it belongs to. It’s precisely this mapping that’s often missing. Typical causes include:
- Header cells that are only formatted in bold but are not marked as header cells.
- Linked cells and multi-level headers, the relationships between which are lost during export.
- Tables that span multiple pages and are split into separate tables as a result.
- Tables that are used solely for layout purposes, such as to arrange text in columns.
- Empty cells that serve as spacers.
The easiest way to sort this out is in the source file: simple tables without merged cells, a proper header row and no tables used for layout purposes. For complex tables, such as those in annual reports, it is worth having them prepared with human verification.
How many PDFs do you actually have?
There’s no one-size-fits-all answer. As a rule, however, a company has many times more PDFs than it realises. Over the years, forms, price lists, leaflets, articles of association and reports end up on the website, and hardly anyone keeps track of them all.
What’s more, not all PDFs are the same. It is not the number of files that determines the effort involved, but the number of pages. A two-page leaflet and a 120-page report are both PDFs, but they present very different challenges.
Here’s how to get an initial overview:
- Look in the media library of your content management system and filter by PDF.
- Search Google for site:your-domain.co.uk filetype:pdf. This will show you which PDFs are publicly accessible.
- For each document, make a note of the page number and whether it is still needed. Take anything that is out of date offline.
Is it always worth checking?
Yes. It’s always worth checking, because without checking you won’t know where you stand. The key is to ensure that checking isn’t just a one-off project, but is firmly integrated into the process. Every new PDF is checked before it goes online, and the existing files are checked regularly. That way, the backlog doesn’t build up again in the first place.
This is already a requirement for public bodies: BITV 2.0 also applies to documents published since 23 September 2018. Organisations covered by the Accessibility Enhancement Act (BFSG) should also include PDFs that customers receive as part of their services.
How to integrate PDF checking into your processes
- Decide who will check PDFs before they are published.
- Automatically check every new PDF before it is uploaded.
- Additionally, manually check tables and alternative text in important documents.
- Correct errors in the source file wherever possible and amend the template to prevent the error from recurring.
- Review your document library at regular intervals and take outdated documents offline.
How ifdb supports you in this
With Access Read, you can check your PDFs directly in your browser and see the status of your documents in seconds. With Access Doc, you can then make them accessible, either individually or as a whole collection. Where a document needs to be 100 per cent accessible, our experts also carry out an additional manual check. Both tools integrate seamlessly into your existing workflows: they are resource-efficient, legally compliant and cost-effective.
Frequently Asked Questions
Is PAC free of charge?
Yes. PAC is provided free of charge and checks PDFs against PDF/UA and the WCAG.
Is a PDF accessible if the automated check no longer shows any errors?
Not necessarily. The automated check confirms that the structure is formally correct. Only a human review – for example, using a screen reader – can determine whether the reading order, tables and alternative text are understandable to a human.
What is PDF/UA?
PDF/UA stands for PDF Universal Accessibility and is the international standard ISO 14289 for accessible PDFs. It specifies how a PDF must be structured technically so that assistive technologies can read it reliably.
Our guide to accessible PDFs shows you how to make verified documents accessible. You can start the free check straight away using Access Read.
My advice if you’ve just discovered countless PDFs on your website
“If you’ve just discovered countless PDFs on your website, I recommend that you check them using Access Read and then convert them to an accessible format straight away using Access Doc. With our bulk upload feature, it’ll all be sorted in a matter of minutes.”
