- Keyword density represents the frequency at which your keyword appears in a piece of content.
- TF-IDF is a weighted formula for keyword density that has become the standard in data mining, user modeling and information retrieval.
- Keyword density was an objective metric Google used to determine the relevancy of a page until SEO strategists learned they could cheat the system with keyword stuffing.
- There’s no proof that keyword density is still part of Google’s algorithm. But there is evidence that naturally including keywords increases relevance for a particular term.
- Tools like Clearscope.io, Yoast and Moz can help you determine an appropriate keyword density.
- Your top priority should always be creating high quality content and a good user experience, not keyword density.
Enterprise SEO is constantly evolving. Ranking factors that used to be foundational are now shaded with nuance. Chief among these is keyword density, which has been embedded in search engine optimization best practices since the very beginning.
So, what is the ideal keyword density percentage in 2021?
What is keyword density?
Keyword density refers to the number of times a target keyword appears within the total number of words on a page.
Sometimes called keyword frequency, keyword phrase density is calculated as a percentage of the total word count on the page. So, it’s not just the number of keywords on your page, it’s a ratio between all content and your keyphrase.
For example, if your target keyword is “cold weather running gear” and the keyword appears three times in a 300-word post, the keyphrase density is 1%. If it appears six times in a 300-word post, the density rises to 2%. You get the idea.
History of keyword density and SEO
It’s almost impossible to talk about keyword density today without going back to the early days of SEO. Back in the beginning, all the way back, early web crawlers were simply advanced library card catalog systems. They needed a way to get users the information they were looking for. So they used each site’s meta data as a “file tab” in their catalog. Websites could update the file tabs with their priority keywords, and that would help Google organize the site into the right place in their index.
However, even the earliest algorithms knew that the site’s on-page content should match what was listed in its meta tags. Google, in particular, also wanted a way for content to reign supreme – even if sites didn’t update their meta tags.
Enter keyword density, which provided a measurable, objective way for Google to understand what each page in its index was about. If a user searched for a particular keyword and a website’s density was high for that keyword, Google could assume that the website was a good fit for the user.
Then, enter the early SEO strategist, who found a way to exploit Google’s well-intentioned rules.
Soon, SEO webmasters realized they could game the system by cramming as many keywords as they could into a piece of content.
Want to rank for “best keyword density checker?” Simply pack that keyphrase into your heading tags, title tags, meta descriptions and body text. This inevitably lead to garbled content that felt forced and unnatural.
Other times, they’d add lengthy footers to the bottom of the page, which contained dozens of keyword variations. Sometimes, they’d even cloak the keyword-rich text by adding white text against a white background. That way, people couldn’t read it but search engines could.
Keyword stuffing worked so well that it also poured into off-page SEO, producing backlinks brimming with exact match anchor text.
Google quickly wised up
It didn’t take Google long to catch on and take action. The Panda update penalized sites with thin content and an unusually high keyword density. It also targeted sites that were blatantly engaged in manipulative tactics like cloaked text. But they didn’t throw away the keyword density metric altogether. They just created more advanced systems for spotting unnatural manipulation of the metric.
Then, they began to balance out their on-site factors with an off-site look at trust signals. This eventually led to the Google we know and love today. Now, a number of trust and usability signals combine with a more in-depth understanding of search behavior to determine a page’s relevance for a given keyword so that Google can give users the best possible experience with the highest quality content.
In a sense, keyword density is still baked into Google’s search algorithm. It’s just much more complicated now.
TF-IDF is a more advanced way that some information retrieval systems measure keyword density. The acronym stands for “term frequency and inverse document frequency.” The system uses a simple formula to calculate the keyword frequency in a given document. Then, it offsets that number with an inverse document frequency number. This de-prioritizes commonly used words and increases the relative weight of the unique keywords.
The resulting formula has become a standard in data mining, user modeling and information retrieval. And that last one includes, yes, search engines. We don’t know if Google uses some variation of TF-IDF in its own algorithm. However, we do know that TF-IDF is a safe bet for simpler vertical search engines to determine relevance.
Does keyword density affect Google rankings?
So, it should be pretty obvious that keyword stuffing will negatively affect your search engine rankings. But is keyword density important at all anymore?
Yes and no.
It’s unlikely that this simplistic look at keywords is still a Google ranking factor. But there’s plenty of evidence to suggest that including keywords and using natural language in your content improves SEO rankings. Doing so reinforces your site’s relevance for a particular term and enhances the user experience.
Keyword density is like a compass. Because it’s fast and objective, it keeps your content tightly focused on a few key concepts.
It’s also an important SEO metric to incorporate into your competitive analysis. Google your intended keyword or use a tool like Clearscope.io and dig into the data behind the results that appear on Google page one. This includes length and type of content, number and type of inbound links and, yes, keyword density.
Note the keyword density for content that’s actually performing well in the search engine results pages for your focus keyword. That’s a good ballpark number to aim for in your own content.
Google handles over 5 billion searches per day, and every single day, 15% of those searches are completely new. “Completely new” as in, nobody has ever searched for those keywords before in human history.
How is this possible?
It’s possible because people don’t search the same way they used to. Voice search and AI have changed how users interact with search engines. It’s now common to see hyper-specific search queries, sentences and questions driving organic traffic.
As a result, long-tail keywords have become more important and focus keywords now play a different role. Relevance is no longer based solely on exact keyword repetition. Each target keyword is essentially a “bucket” that holds plurals, modifiers, rephrased searches, questions and other highly-related search terms (but not synonyms). And when a keyword becomes a bucket, it’s hard to determine a true keyword density for that term.
You still can and absolutely should optimize for specific keywords that pull in a verifiably high search volume. Just know from the outset that you’re not optimizing for those terms alone. You’re also optimizing for the hundreds of related keywords and searches that come with a major keyword. And while high-opportunity anchor terms are a smart way to organize your site and provide a foundation for your SEO strategy, they are difficult to reverse-engineer when it comes to true keyword density.
It’s all about user experience
Let’s get back to that 15% of all searches that are new. These searches have prompted Google to start indexing more semantically as their RankBrain algorithm grows ever smarter.
So, when a user Googles “where to find bats,” they may be looking to purchase baseball bats. Or they might be making a list of day-trip ideas to go see their favorite furry, flying mammals in the wild.
To determine which is true and provide the best content, Google will pull in personalized context like the user’s Google search history and location. But Google also has ways of determining whether your web page is contextually relevant for a certain keyword.
Let’s say you’re trying to rank for the keyword “best project management software.” No amount of keyword density optimization is going to help you. That’s because when people search for something like “best” they’re probably looking for third-party reviews rather than a single platform’s sales page.
However, your site does have a chance to rank for that keyword if it provides the contextual clues Google is looking for. In this case, an in-depth blog post offering comparative keywords, reviews and types of platforms will be much more in line with search intent. It’s a slight oversimplification, but here’s the easiest way to think about semantic indexing. Google thinks in topic clusters. The more you thematically organize your content to provide context, the more relevance you’ll establish for your target keyword.
How to calculate your ideal keyword density for SEO
So, where does this leave us when it comes to the optimal keyword density? It’s certainly not a metric you should just ignore. But rather than aiming for an exact percentage, use it as an objective guidepost for your content. Here are a few keyword density best practices:
- Google doesn’t have a hard-and-fast recommended keyword density.
- Measure and benchmark the keyword density for the top-ranking content in Google for your target keyphrase.
- You can also reference the keyword density for your own top-ranking content for similar topics.
- Keyword density tools like Yoast set a density range of .5% to 3%, but you should do what feels natural and provides the best user experience.
- As you build out the topical focus of each page, map out a few keywords that are contextually or semantically-related to your target keyword (synonyms, variants, closely related topics, etc.) and work these into your content. Use tools like Clearscope.io, which can scan competing content to see what related terms and keywords the top performing pages use.
Your first priority should always, always be to create high quality content that offers an amazing user experience. This is more important than keyword density for any page that you develop.
Keyword density tools
There are a few different SEO tools you can use to measure the best keyword density. We like the following:
The WordPress SEO plug-in Yoast is far more than just a keyword density checker. But it is a great way to get an instant, no-nonsense read on your focus keyword density as you build out your content or page. Just know that Yoast’s goal is to simplify the SEO process via objective metrics. So its recommendations won’t always make sense on a case-by-case basis. Yoast Premium has taken steps to recognize different word forms as one keyword. And your keyword can also be broken up in the same sentence to count as a “mention.” If your keyword is broken up over multiple sentences, though, the tool does not register it. It also has a hard time with synonyms and can’t tell how well your content contextually reinforces the focus keyword.
Overall, Yoast’s tool isn’t a perfect match for Google’s semantic indexing style. But it’s a quick and easy way to keep track of any individual goals you set based on your SERP research. And if you exceed Yoast’s upper limit, there’s a pretty good chance you’ll need to take corrective action and add some variety to your post.
Moz On-Page SEO Grader
Moz’s On-Page Grader provides a more robust look at keyword density. Enter a url and a focus keyword into the tool. Then, Moz will score the page on several factors, including keyword density, page title and much more. The tool also targets any keywords your competitors are using that are related to the focus keyword. This gives you ideas that can broaden your content and increase your topical authority. The SERP-based competitor analysis makes this a great tool to incorporate into the preliminary part of your keyword research too, not just at the end.
In short, there’s much more to keyword density than meets the eye. Your top priority should always be to produce high quality content for a great user experience. So as long as you keep context in mind, you can use the keyword density metric to create content that thrills your audience and drives conversions.
Want to dive deeper? Check out our post about on-page SEO.