What is keyword density?

When it comes to ranking a website at the top of the SERPs only the search engines themselves know exactly what mix of ranking factors create a great ranking, but you would be hard pressed to find a marketer that doesn’t agree that on-page optimization is important. In fact, if you are exploring SEO tutorials and courses a large portion of them will tell you to begin by optimizing your on-page. Consider the fact Google has multiple algorithms that deal with quality content, original content, title tags, and page speed and it is easy to see how important your on-page optimization is.

Part of your on-page optimization is deciding which keywords to optimize for and where and how often to place those keywords. How often your keyword appears on your website is known as “keyword density” and it may be one of the most mysterious and difficult things to get right. Understanding keyword density and how it affects your rankings is key to a successful on-page optimization campaign. Too low of a keyword density and the SERPs may not correctly identify what your website is about. Too high of a keyword density and you may be hit with a penalty for “keyword stuffing”.

Calculating keyword density is a pretty straightforward process. Compare how many words are on the target page to how many times your keyword appears and you will get your keyword density. For example; if the page we are targeting has 100 words on it and our target keyword appears 10 times in those 100 words then the keyword density is 10%.

In the past, it was easy to get keyword density right. Just put your keyword into your written copy as many times as you can. The search engines were not smart enough to see the content’s quality so it relied on how many times a keyword appeared to determine how relevant the website was to the query used. As AI gets more intelligent and the ranking algorithms that the SERPs employ get more complex, the practice of keyword stuffing has become a thing of the past.

Search engines want to provide results that are the most relevant and valuable to the searcher. If we, as marketers and website owners, want to meet that requirement and appear first when a user goes looking for the service or product we provide than we must be able to provide relevant and high quality content that is easy to read and appears natural. It is for this reason that we must be aware of keyword density.

So, what is the right keyword density?

That is where things get really complicated. There is no perfect answer here. Marketers have been trying to answer this question with certainty for a few years now but the conclusion is always the same; we can’t say for sure. Some would say 1%-3% with 1.5% being ideal, but if you are using certain SEO plugins on your Wordpress website you will notice they want 0.5%-2.5% and provide no recommended ratio.

With so many different opinions out there the only thing we can rely on is hard data. To that end, we analyzed 11 search queries in various industries. We took the top 5 search results for a 2 word query and analyzed the keyword density for that exact query, meaning we did not consider even the smallest variation of the given search term. We also left out directory sites and paid ads to ensure we were not getting skewed results.

Top 5 websites ranged in average keyword density from 0.354% up to 4.462%. Even within a single industry we saw big swings. “Plastic surgery” for example varied from 1.15% keyword density up to 3.710%. There were even some results in which the keyword density was at 0% for 3 position, but 0.89% for fourth position.

Which brings us to the next point of consideration. Why would a website rank at all for a given search term if the site does not contain the query at all? The bigger question here is; how can that same site with 0% keyword density beat a website that contains the exact search term?

Latent Semantic Index to the rescue!

As search engine AI and algorithms improve, they learn to recognize context and phrasing. This is what we call “Latent Semantic Index”, or LSI. This improvement to the website indexing process has created an index that is closer to how a human might categorize documents.

LSI works by comparing all of the words in a web page and determining how close or far apart they are semantically. It uses the context of a website to determine the meaning of words, which allows search engines to more accurately determine what a website is about, and it’s relevance to a searcher’s query.

For example, consider the word “cool”. This word can have multiple meanings depending on how it is used. If someone says to you “the weather should cool down today” you know that they are referencing the temperature and its relationship to today’s weather. However; if someone says to you “that girl is pretty cool” you know they are not talking about her temperature.

It is because of the surrounding words and the context of the conversation that you are able to know the difference between temperature and temperament. LSI helps search engines like Google make that same distinction. LSI is also the reason a website that does not contain a specific keyword can outrank one that does.

What does it all this mean for on page SEO?

Gone are the days of writing content designed for search engines. The search engine providers want content that is designed to benefit a website visitor and add value to their searches. This is how they will continue to grow and continue to sell advertising space. Content creators need to learn how to create content that is shareable and usable for everyone. They cannot continue to keyword stuff their content.

In a lot of ways, this actually makes life a lot easier. Now, content can be created in a natural way. Creators can speak to their audiences instead of trying to speak to a machine and hoping that machine understands what is being said while at the same time convincing humans that the website contains the valuable information that they are looking for.

There are also a lot more ways to find and obtain profitable traffic due to “long tail keywords”. Long tail keywords are those keyword phrases that are more like full sentences as opposed to a few words that can drive traffic for the savvy content creator that can find and target them.

We also need to be more careful of those that we hire or outsource to when it comes to the copy that appears on our site. Writers that understand SEO, at least at a basic level, are going to be those that are more successful when it comes to selling their services to marketers and website owners. Writers need to be aware of the impact keyword stuffing can have, and need to understand latent semantic indexing and how it can be used in their writing. Writing needs to be specific for websites and SEO.

For website visitors, this is good too. There are a lot of people that remember the time when search results had to be filtered to find the content that they were actually looking for. These days, search queries return quality content in just a few results and most of our answers are found in the top 3 to 5 websites that appear. It is due to the evolution of the search engine algorithms and innovations like latent semantic indexing that has helped the internet to mature into the tool that we use every day.

Keyword density is actually a very small part of the search engine ranking algorithm, but it is essential that it is understood. Even the best keyword density strategy will not rank a website by itself, but falling victim to its pitfalls can invite a ranking penalty very quickly.