Search engines aim to index as much content as possible from every website on the internet. Through a variety of unintentional or purposeful mechanisms, search engines can’t necessarily read, index or find every piece of content – however, many forms of content are easily found with a variety of customized search commands.

PDFs are but one example of non-traditional content that can feature prominently in search results. These files are versatile and make it easy for users to view, download and save entire pages or data-sets, but are they helpful for brands, blogs and businesses seeking to improve SEO potential?

Let’s take a look at what PDFs offer websites in terms of SEO performance and search visibility.

How Search Engines Read PDFs

Given that search engine indexing of content is the most important factor in search engine visibility, understanding how search engines assess PDF documents is very crucial. While every search engine may have its own methods, the largest – Google – uses a straightforward system. PDFs are indexed by Google by first converting their contents into HTML format just like any standard web page. This allows the search engine to understand its content and context, better ranking it in key search results.

If PDFs are duplicated in other formats (such as standard web pages), then Google will generally default to the non-PDF format for indexing. Ultimately, pinging to Google or any search engine a large number of PDFs will result in them being indexed – but if their contents can be found in other formats, then those files/pages will likely rank more prominently.

Where PDFs Fall Short for SEO

Even though search engines can quite easily index and read the content in any PDF document, they aren’t necessarily an ideal format for SEO purposes.

First and foremost, PDF files are often not optimized for mobile audiences. This means that mobile-specific search results won’t be likely to display these files. Ultimately, using PDFs to rank in select SERPs can leave your SEO efforts falling short in what will surely be a majority of searches for a particular keyword, niche or SERP.

PDFs also often fail to include various links or navigational features that make browsing easy. As such, somebody who clicks on a PDF may not find it very helpful and can quickly exit the document in search of better alternatives. This of course can affect multiple variables that search engines evaluate in terms of SEO quality, like bounce rates.

Likewise and given the usual static nature of PDF files, search engines may not assess this content often. This means it will not be indexed often; generally speaking, the more often your pages and content are indexed, the more positive signals you’re pinging to Google and other search engines. For this reason and others, if the contents of a PDF document can be incorporated into a standard web page, blog post or other similar format, it is recommended.

While there are some situations in which the use of PDF documents are simply unavoidable, common use can hinder otherwise meaningful progress for your SEO endeavors. If there are any alternatives, we generally recommend their use due to indexing, mobile-friendliness and other factors that search engines care about when assessing user experience and technical SEO considerations.