Are PDFs Optimal for SEO?
Should You Use PDFs in Place of a Web Page?
The purpose of a PDF is written in its name—it stands for Portable Document Format. Adobe Acrobat designed PDFs to open with the same formatting and content across all operating systems. This makes PDFs ideal for content that requires graphics and text to remain in the same position, usually meant to be viewed as a hard-copy. Although Adobe has since developed features that support PDF editing (form-fills, e-signing, etc.), the PDF was originally praised for its consistency—especially in printing. Keeping this in mind, these are the pros and cons of PDFs:
- Formatting consistency (on-screen and printed)
- Inexpensive to create
- Accessible without internet
- Font, images, and other elements are embedded (independent of browser)
- Fewer, more costly interactive features
- Requires a PDF reader to open
- Files can become excessively large
- Less opportunity for SEO and data analytics
What is HTML to SEO?
HTML is a web language. Websites are interactive, so web developers use HTML to make interactive elements—buttons, moving graphics, videos, and the like. One major difference between HTML and PDFs is file structure. While all elements are embedded in a PDF (this is necessary for its primary purpose of consistency), HTML stitches together a collection of files from an external source(s). From an SEO standpoint, this is often a positive—each individual piece can be easily tracked and crawled by search engines. It is also positive from a user experience perspective, which values the viewer’s ability to adjust her own on-screen experience by, for example, changing the browser size. In turn, she can read content with shorter or longer line lengths as she pleases. The biggest downfall of the HTML file structure is its dependence on browser and operating system compatibility for, say, fonts. However, assuming the HTML is properly developed and is compatible, the format is highly adaptable and adjusts to almost any platform.
- Highly interactive
- Adaptable to most browsers/operating systems
- More opportunity for SEO
- Can include rich media (videos, audio, etc.)
- Adjustable on-screen appearance
- Dependent on browser/operating system compatibility
- Not designed for consistency when printing/saving to local drive
- Difficult to access without internet
When to use PDFs instead of HTML
As a rule of thumb, HTML is a better option than PDFs when it comes to search engine optimization. However, there are a few instances where PDFs can be beneficial:
- Content meant to be printed (or viewed as printed on-screen)
- Content containing special symbols, especially for math
These instances assume you’re starting from scratch; you haven’t made HTML or PDFs for your content yet. Of course, every situation is unique. If you already have a few well-designed PDFs on your site that are getting traction, it’s not the end of the world if you don’t create HTML for them instead—just make sure they’re as SEO-friendly as they can be.
Checklist for Optimizing PDFs for SEO
- Create a relevant title tag
- Use text-based PDFs
- Include alt tags for images
- Add internal links and backlinks
- Select relevant keywords
- Reduce file size