Optimize PDF SEO the Right Way!

Now all the necessary measures for search engine optimization (also: SEO) have been taken, and the website achieves the best rankings? Even if the first steps have been successfully mastered, the next step is - SEO for PDFs!
The PDF file doesn't have a good reputation in the SEO world, but sometimes you can't do without it. This is partly due to the static format (HTML pages cannot be downloaded as easily) and partly due to the user experience: Some people prefer to read certain content offline, and PDF files typically provide detailed information that may not always be suitable for HTML pages due to text length (extreme scrolling and unnecessary information can in the worst case lead to bounce rates). So PDF files have their own target audience that can and should be addressed. Therefore, optimizing PDFs for search engines is worth it, even though it comes with some challenges.

Back to the roots: History and relevance of PDFs

Anyone who regularly uses Google search knows that you can find not only websites but also PDF documents in the organic search results. In fact, PDF files have been in the Google Index since 2000:

PDF file in Google Search - https://www.internetwarriors.de/

The PDF format (Portable Document Format) has existed since the early 1990s - developed by Adobe Inc. - and can contain text, images, forms, links, etc. Nowadays, it stands for the open standard (ISO) and is very popular due to its accessibility.
The inclusion by search engines enabled users to have broader access to information. This added value led to the aforementioned indexation of static PDF files. This was the starting signal for another discipline of search engine optimization: SEO PDF.
Although PDF files differ from the “classic” web formats, they also offer numerous advantages for search engine optimization. It’s not just about the benefit for the users but also about keywords (PDF files can be excellently optimized for keywords), backlinks (PDFs as a source for backlinks), and durable content. Therefore, if they are well integrated into the SEO strategy, PDFs can provide significant added value.

Search Engine Optimization for PDF: How to do it right!

To understand how PDF documents can be optimized, two main questions arise: How does Google rank PDF files? What determines their position compared to websites? And ultimately - what distinguishes PDF files from classic websites? Two points stand out:

1. PDFs are usually longer

2. Users generally link less frequently to PDF documents

In general, Google itself says that assessing relevance is difficult because it also depends on personal taste, whether a user prefers to read a PDF or a website. The handling by different search engines varies, so only a few tips can be given here that might be helpful. Here you can find out which ones they are!

But first a golden rule: Google, as a text-based search engine, requires real text to optimally read and evaluate a document. PDF documents often consist of images, especially when it comes to scanned book pages or something similar. With the help of OCR software (Optical Character Recognition - a technology familiar to many from scanners), Google may in the future be able to read images containing text better, but until then, pure text documents are the better choice. This is where SEO optimization for PDF begins:

Format, adjust, and reformat

As mentioned earlier, the SEO optimization of PDF begins with a correct file format. It's very easy to check if it’s correct: If text from a PDF document can be copied & pasted into a Word file, for example, it is real text. Even if there are tables in a file, they should also be text-based. Selectable text is not the only requirement for a correct format. Besides the text content, other aspects must be considered, such as file size. If you follow the principle “as small as possible,” you can practically do nothing wrong in this regard. Generally, file size reflects the loading speed and download duration. In general, any size under 1 MB is considered user-friendly, but some PDF files require more, which is justified by the amount of content. Furthermore, the size range between 1 and 5 MB can be considered optimal, with everything over 1 MB intended for large files and documents. It’s also important to keep in mind that images should be compressed as best as possible to avoid unnecessarily increasing file size. You should always ask yourself if the file size matches the intended use and emphasize the user experience.
The write protection of PDF files should not be neglected - it is important primarily to prevent changes and modifications to the original files. Crawlers do reach write-protected PDF files, but indexing them is not very useful. It's recommended to set such PDF files to noindex. 
In conclusion, proper formatting is the first step in the SEO optimization of PDFs. It also ensures readability and accessibility, which are essential for a positive user experience.

The content determines success

“Content is King” seems to be one of the best-known and most current quotes, although it originated from an essay by Bill Gates from the distant year 1996. Nowadays, the phrase has become a kind of cliché and has found its place in the world of online marketing. It is also a mandate in search engine optimization when it comes to content creation. PDF files are not exempt from it.
As always, the rule applies - it’s all about the users. Therefore, the PDF file should also offer added value if a good ranking is to be achieved. There must not only be SEO optimization of the PDF but also informative, relevant, and useful content for the user. Added value, quality, and credibility are crucial for E-E-AT optimization, so it’s even more important to create high-quality content.
The content optimization for PDF files follows the same rules as for “normal” HTML pages - one of the most important: It must be unique. This means: PDF files should provide additional information to the content of HTML pages, may complement them, but must not be identical. This leads to the issue of duplicate content. However, if there is a good reason to duplicate the content, a canonical tag must not be forgotten.
There are hardly any differences in keyword optimization: PDF files should and must be keyword optimized, as search engines find and index PDFs through relevant keywords. However, care should be taken to ensure that the keywords are integrated as naturally as possible into the content and also appear in headings, title tags, meta-descriptions, and file names.

PDF Mastery: On-page optimization for maximum success

An on-page optimization is also required for PDF SEO. Fundamentally, it is very similar to the on-page optimization of HTML pages. If done correctly, you can benefit from findability, user experience, and accessibility.
The first step is to take care of the file name: It should be as descriptive and simple as possible. Adding a meaningful keyword to the file name is a helpful step, as it facilitates indexing by search engines. However, special characters should not be used but rather hyphens - this measure serves, among other things, better compatibility (for various software and operating systems), URL friendliness, and error prevention (special characters have specific meanings in the file system).
In the next step, the title, which is part of the metadata, should be optimized. Here the generally known SEO rules apply - length (max. 60 characters), unique design, relevant keywords, and brand at the end of the title. The title is stored directly in the PDF file and is a crucial part of PDF SEO. It is also possible to store the file name as the title simultaneously, which is also a permissible implementation. This must now be noted in the settings (Adobe Acrobat).
In comparison to the title, the meta description or description is not entirely identical to what is known from SEO optimization. For PDF files, metadata includes title, author, keywords, and content summaries. Moreover, additional metadata can add further information. Except for the keywords, which nowadays have no relevance for ranking, all fields must be filled out. Even with a different handling of PDF files, it is recommended to pay attention to the description length (max. 160 characters) and add a usual call-to-action.
Headings play a special role in SEO traditionally: They…

• …structure the content for users and search engines

• …provide an excellent opportunity to incorporate keywords for a better ranking

• …improve the user experience

• …facilitate navigation especially for users who rely on screen readers

• …highlight the content

Besides, headings are an important ranking factor. Therefore, it is crucial not only to equip websites but also PDF files well with headings. The same rules as for HTML pages should be followed - no unnecessary headings, keyword optimization, one H1 per page or document, and pay attention to a logical order. Adding headings is very straightforward using Adobe Acrobat (or PDF-XChange Editor) or already in the Word file (with subsequent export of the document as PDF).
If content is seen as king in the SEO world, then internal linking is at least a hidden bridge to SEO success. Even for PDFs, internal linking is very relevant as it can increase the value of the PDF file itself and its visibility. Furthermore, internal linking can be very well implemented through relevant keywords in the content. It is only necessary to maintain a thematic connection and link to pages that themselves match the content of the PDF file. Also, anchor texts and integration into the sitemap should not be forgotten. When backlinks from high-quality websites refer to the file, there is an excellent opportunity to improve authority and visibility and thus integrate into the E-E-A-T concept. Additionally, internal linking can hardly be dispensed with if you want to optimize PDFs for SEO.

Tech-Tuning: Optimize your PDF!

When content, keywords, and on-page are optimized for PDF files, the first half is done. The next and almost last step should be technical optimization.
Inclusion in the sitemap is very important for universal and/or current PDFs. However, the added value should be assumed - does the PDF file offer it to the user? If this question can be positively answered and the criteria are met, then the sitemap is the right place for the PDF files. The advantages are similar to HTML pages - direct indexing, better discoverability, better performance, and proactive control of the indexing process. However, if you want to exclude certain files from indexing, this can also be done using the “noindex” tag.
The canonical tag should be correctly set and used: Is the content of the PDF similar or even identical to the content of the HTML page? Then the canonical tag is indispensable to avoid the problem of duplicate content.
SEO optimization of PDF also requires mobile optimization - accordingly, the aspects should be considered that characterize a mobile-friendly file - starting from the file size (should not be too large) to correct formatting (e.g., portrait orientation, left-aligned text, use of sections & headings, good structuring, etc.) When these points are considered, the search engine optimization for PDFs is on the right track!

PDF without barriers: Redefining accessibility!

The topic of web accessibility has long been on everyone’s mind - and for good reason! Websites should be accessible to everyone and, come June 2025, this will become mandatory. Therefore, fundamental adjustments should also be made in PDF files:

• All graphics/images should be provided with alt texts

• Headings and tags must also be implemented

• Content must not only be text-based but also have the necessary contrast and a comprehensible font

• Last but not least: The necessary configurations for the use of screen readers must not be forgotten.
  
  The good news is that all these measures can be directly implemented in PDF programs like Adobe Acrobat or the PDF-XChange Editor. Subsequently, the accessibility check (which is also available in the programs) can be called to verify implementation.

Accessibility SEO PDF

PDF Tracking: Measure with precision

If you want to make performance measurable, you should definitely consider tracking. This is also a part of PDF SEO and can be used effectively. This gives you a way to track user interaction with the PDF file. There are many methods suitable for tracking PDF files - everyone can find the right one for themselves. However, the concept of tracking should be approached carefully and always weighed if it's necessary.

SEO Optimization for PDFs: Strategies for Success

Even though PDF SEO is considered complicated, it is worth optimizing such files correctly. It should not be underestimated that PDF files can be SEO relevant for several reasons:

• Indexation of content (text-based)

• additional opportunity for keyword optimization

• positive user experience

• distribution of link equity

• sustainable content

PDFs are thus a valuable addition to the website that represents a content expansion, addresses specific target groups, and can increase visibility with appropriate optimization. If you stick to the rules and properly implement search engine optimization for PDFs and fundamentally incorporate the use of PDF files into the SEO strategy, you can only benefit from the extended content format!
Need help optimizing your PDF content? Don't hesitate to contact us - our team is happy to assist! It's that easy: Schedule an appointment and get all the insights! Discover more about our SEO services!