November 15, 2017

Accessible PDF Versus HTML5: What Does Each Format Have To Offer?

Jen Goulden | Project & Quality Manager
Document Accessibility Webinars

What are the differences between Accessible PDF and Accessible HTML5? Is one of them better than the other? These are questions participants often ask us during presentations on document accessibility. Discussing the differences – and the similarities – between these two electronic formats is relatively straightforward. However, the question of whether one is better than the other depends on a number of factors. This is especially true in the field of document accessibility.

One of the main reasons that screen reader users sometimes prefer HTML is that a PDF file can be anything from a perfectly tagged, accessible document to a scanned image of a handwritten note. Since screen readers are designed to convert text to speech they cannot process images. When the end user opens a scanned PDF, the screen reader will say that it is an “empty document”. This is not a risk in HTML5. If this happens to you often enough with PDF files, it makes sense that you would prefer another format!

The content of a document and the platform on which you are going to read it will also affect your choice of format. We generally associate PDFs with documents and HTML with web content. For example, you may be happy to access a bank statement online in HTML5, but if you need a hard copy you’ll want to download a PDF. On the other hand, you probably don’t want to read a 30-page insurance policy in HTML5, regardless of whether or not you need a hard copy.

Any consideration of electronic formats must include mobile technology. Accessing information on smart phones is becoming the norm, and the accessibility features built into these devices has been a game-changer for individuals who are unable to read conventional print. Both formats allow the screen reader user to navigate to specific elements in the content, such as headings, lists and tables. Having said that, Accessible HTML5 offers a much better user experience on a mobile device. Accessible PDF files are not easy to navigate unless the user downloads a PDF reader such as the Acrobat app.

Although there are many differences between Accessible PDF and Accessible HTML5 it is important to note that for the most part, the screen reader commands used to navigate both formats are the same. Navigating by headings, pulling up a list of links and jumping to the next table require the same keyboard commands whether the end user is reading a PDF or an HTML5 file. Although different software is used to create each file type the same elements (e.g. headings, paragraphs and tables) are tagged. Both formats require alt text descriptions to be added to images.

The reality is that both Accessible PDF and HTML5, if properly coded or designed, can provide an excellent user experience. As to the question of which is better, like so many other aspects of document accessibility, the answer will depend on the document type, the end user’s assistive technology and even their reason for requesting the information in the first place.