Optimize PDF SEO the Right Way!

Now that all necessary measures for search engine optimization (also: SEO) have been taken and the website achieves top rankings? Even if the first steps are successfully mastered, the next step comes - SEO for PDFs!
The PDF file is notoriously not well-regarded in the SEO world, but sometimes it's unavoidable. This is partly due to the static format (HTML pages are not as easily downloadable) and partly due to the user experience: some people prefer to read certain content offline, and PDF files usually provide detailed information that isn't always suitable for HTML pages due to text length (extensive scrolling and unnecessary information can, in the worst case, lead to bounce rates). So PDFs have their own target audience that can and should be addressed. Therefore, optimizing PDFs for search engines is worthwhile, even if it brings some challenges.

Back to the roots: History and relevance of PDFs

Regular users of Google search know that organic search results can include not only websites but also PDF documents. In fact, PDF files have been in the Google index since the year 2000:

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

The PDF format (Portable Document Format) has existed since the early '90s - developed by Adobe Inc. - and can contain both text and images, forms, links, etc. Today it stands for the open standard (ISO) and is very popular for its accessibility.
The inclusion by search engines allowed users a broader access to information. This added value resulted in the discussed indexing of static PDF files. This was the starting shot for another discipline of search engine optimization: SEO PDF.
Though PDF files differ from 'classic' web formats, they offer numerous advantages for SEO. This isn't just about the profit for users, but also about keywords (PDFs can be excellently optimized for keywords), backlinks (PDFs as a source for backlinks), and enduring content. Therefore, when well-integrated into the SEO strategy, PDFs can provide significant added value.

Search engine optimization for PDFs: Doing it right!

To understand how to optimize PDF documents, two main questions arise: How does Google rank PDF files? What decides their position compared to websites? And ultimately - what differentiates PDFs from classic websites? Two points stand out:

1. PDFs are generally longer

2. Users tend to link less to PDF documents

Google itself also says that determining relevance is difficult because it depends on personal preference whether a user prefers to read a PDF or a website. Different search engines handle this differently and so only some helpful hints can be provided here. Find out what these are!

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

Formatting, adjusting, and reformatting

As mentioned, PDF SEO optimization starts with the correct file format. It's simple to check if it’s correct: if text from a PDF document can be copied and pasted into, e.g., a Word file, it is real text. Even if tables are present in a file, they should be text-based. Selectable text isn’t the only requirement for the correct format. Besides the text content, other aspects need to be considered, such as file size. Following the principle “as small as possible” practically ensures you can’t go wrong in this regard. Generally, file size reflects loading speed and download duration. A size under 1 MB is generally considered user-friendly, but some PDFs require more, justified by the amount of content. Additionally, a range between 1 and 5 MB can be seen as optimal, with anything over 1 MB aimed at large files and documents. It’s important to consider image compression to prevent unnecessarily increasing the file size. Always ask whether the file size suits its purpose and prioritize user experience.
Don’t overlook the write protection of PDFs - it’s crucial to prevent changes and modifications to the original files. Despite crawlers accessing write-protected PDFs, indexing them is usually pointless. It’s recommended to set such PDFs to noindex. 
In summary: Correct formatting is the first step in PDF SEO optimization. It also ensures readability and accessibility, essential for a positive user experience.

Content determines success

“Content is King” seems to be one of the most well-known and current quotes, even though it originates from a 1996 essay by Bill Gates. The saying has become somewhat of a cliché and has its place in the online marketing world. It’s also a rule in search engine optimization when it comes to content creation. PDFs are no exception.
The rule always applies - it’s all about the users. Thus, the PDF should provide added value if a good ranking is to be achieved. It needs not only SEO optimization but also informative, relevant, and useful content for the user. Added value, quality, and credibility are crucial for E-E-A-T optimization, making it essential to create high-quality content.
Content optimization for PDFs follows the same rules as for 'normal' HTML pages - one of the most important: it must be unique. This means: PDFs should provide additional information to the HTML content, may complement them, but must not be identical. This leads to the issue of duplicate content. If there’s a good reason to duplicate content, a Canonical Tag must not be forgotten.
In terms of keyword optimization, there are almost no differences: PDFs should and must be keyword optimized because search engines find and index PDFs through relevant keywords. Care should be taken to integrate keywords as naturally as possible into the content, and they should also appear in headings, title tags, meta descriptions, and file names.

PDF Mastery: Onpage optimization for maximum success

An onpage optimization is also required for PDF SEO. Essentially, it is very similar to onpage optimization of HTML pages. When done correctly, discoverability, user experience, and accessibility can benefit.
The first concern should be the file name: it should be as descriptive and simple as possible. Integrating a meaningful keyword into the file name is a helpful step, as it facilitates indexing by search engines. However, avoid using special characters and prefer hyphens - this measure is partly for better compatibility (for various software and operating systems), URL friendliness, and error avoidance (special characters have specific meanings in the file system).
Next, the title, part of the metadata, should be optimized. Common SEO rules apply here - length (max. 60 characters), unique design, relevant keywords, and brand at the end of the title. The title is directly stored in the PDF file and is an essential part of PDF SEO. It's possible to save the file name as the title simultaneously, which is also a permissible implementation. This must now be noted in the settings (Adobe Acrobat) accordingly.
Contrasting with the title, the meta description or description is not quite identical to what is known from SEO optimization. For PDFs, metadata includes title, author, keywords, and content summaries. Additionally, further information can be added via additional metadata. Except for keywords, which no longer have ranking relevance, all fields must be filled out. Even with different handling of PDF files, it is advisable to still consider the description's length (max. 160 characters) and add a usual call-to-action.

Traditionally, headings play a very special role in SEO:

• …they structure content for users and search engines

• …provide an excellent opportunity to integrate keywords for better ranking

• …improve user experience

• …facilitate navigation, especially for users relying on screen readers

• …highlight content

Moreover, headings are an important ranking factor. Therefore, it's crucial to equip not only websites but also PDFs with good headings. The same rules as for HTML pages should be followed - no unnecessary headings, keyword optimization, one H1 per page or document, and maintaining logical order. Inserting 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 considered a king in the SEO world, then internal linking is at least a hidden bridge to SEO success. Internal linking is also very relevant for PDFs, as it can increase the value of the PDF itself and its visibility. Internal linking can be well implemented through relevant keywords in the content. It is merely necessary to maintain thematic coherence and link to pages that fit the PDF's content. Moreover, anchor texts should not be overlooked, nor should the embedding in the sitemap. If backlinks from high-quality websites point to the document, there is an excellent chance to improve authority and visibility and thus work into the E-E-A-T concept. Furthermore, internal linking is almost indispensable if one wants to optimize PDFs for SEO.

Tech-Tuning: Optimize your PDF!

Once content, keywords, and onpage aspects for PDFs are optimized, the first half is done. The next and almost last step should be technical optimization.
Including it in the sitemap is essential for universal and/or current PDFs. However, one should start with the added value - 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 PDFs. The advantages are similar to HTML pages - direct indexing, better discoverability, improved performance, and proactive control of the indexing process. However, if certain files are to be excluded from indexing, this can also be done using the “noindex” tag.
The canonical tag should be correctly used and applied: Is the PDF content similar or even identical to the HTML page content? If so, the canonical tag is indispensable to avoid the issue of duplicate content.
The SEO optimization of PDFs also requires mobile optimization - correspondingly, aspects that characterize a mobile-friendly file should be considered - starting with file size (shouldn't be too large) to correct formatting (e.g., portrait orientation, left-aligned text, use of sections & headings, good structuring, etc.). If these points are observed, PDF search engine optimization is on the right track!

PDF without barriers: Accessibility redefined!

The topic of web accessibility has been discussed for a long time - and rightly so! Websites should be accessible to everyone, and from June 2025, this becomes mandatory. Hence, basic adaptations should be made in PDFs:

• All images/graphics should have alt texts

• Headings and tags must also be implemented

• Content must be text-based but also need appropriate contrast and readable typeface

• Lastly: Don’t forget necessary configurations for screen readers.
  The good news is that all these measures can be directly implemented in PDF programs like Adobe Acrobat or the PDF-XChange Editor. Afterward, you can use the accessibility check (also available in the programs) to verify implementation.

SEO PDF Accessibility

PDF Tracking: Measuring with Precision

Those wanting to measure performance should definitely consider tracking. This is also part of PDF SEO and can be used effectively. It provides a way to understand how users interact with the PDF document. There are many methods suitable for tracking PDF files - everyone can find what works best for them. However, the tracking concept should be approached with caution, always weighing its necessity.

SEO Optimization for PDFs: Strategies for Success

Even if PDF SEO is considered complex, it’s worth optimizing such files correctly. It should not be underestimated that PDFs can be SEO-relevant for several reasons:

• Indexing 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, offering content expansion, targeting specific audiences, and appropriately optimized can increase visibility. If you follow the rules and properly implement search engine optimization for PDFs and fundamentally include the use of PDF files in the SEO strategy, you can only benefit from the expanded content format!
Need help optimizing your PDF content? Don't hesitate to contact us - our team is happy to assist you! It's simple: schedule an appointment and get all the insights! Learn more about our SEO services!