Keyword Density

A tag cloud showing keyword density visuallyWhat’s a keyword?

In SEO terms, a keyword is a word or phrase that you’re aiming to have your website listed under in a search engine result page.

What’s keyword density?

Keyword density refers to the frequency that the word or phrase appears in a given page, page title or link, relative to other content. This includes HTML, as well as plain text.

The importance of keyword density in SEO

Many years ago search engines used keyword density as one of the primary factors when ranking a page. In an ideal world, where no-one abused this system, this would actually be a good way of returning relevant results. However, website owners (like yourself no doubt) wish to appear as close to the top of search engine results pages as possible for their preferred phrases and in itself, basing search matches purely on keyword density for a given word or phrase means it’s too easy to feature and repeat potentially irrelevant text in an effort to get an artificially high ranking.

Search engines became wise to this and added keyword stuffing filters to penalise websites for overusing keywords in an attempt to artificially boost rankings.

As more intelligent logic has been written into search engines to base ranking and importance on other factors, the importance of keyword density has diminished somewhat, but search engines still base their categorisation of your website largely on keyword density and still penalise you for deliberate overuse, so it’s still something to be mindful of.

Striking a balance

There’s no perfect formula that will make all search engines rate your content highly, but it’s generally accepted that a keyword density of over 5% on a web page can be seen as suspicious. At the opposite end of the spectrum, if a keyword you’re trying to rank highly for is not mentioned often, it’s hard for search engines to know that your content is relevant. It’s worth using one of the many free keyword density tools out there to check important pages on your website, to ensure you’re not wildly overusing keywords. It’s also worth checking out high ranking competitors websites to see what content works with the search engines and with users.

The best advice is to write copy relevant to a particular subject and stay focused on it. This will produce content that users want to read (which will encourage users to return and recommend your website to others) and search engines have enough logic built into them to recognise naturally written, genuinely useful text as exactly that.


Search engines look for context in page content, so will assume your page is more relevant to a keyword search if it contains a balanced mix of other semantically related phrases that are deemed relevant, with similar keyword density to your keywords.

Keyword density in page titles and links

Page titles can be regarded with as much importance as page content, so you need to have key phrases for your page there, but don’t repeat a phrase more than twice (e.g. Bob’s cars – car stereos, tools for cars, car wheels) as it’s likely to be seen as keyword spam. It’s also not useful for users to be confronted with page titles full of repetition in search engine listings.

Links within your website and on other sites linking back to yours should be treated in the same way. They need to feature your key phrases, but not repeated. If you have influence on how external websites link back to your site, it’s worth varying the link text a little, as linking back with identical text can be seen as unnatural and suspicious.

Long tail SEO - the red curve shows long tail content producing a more even spread of traffic than traditional content represented by the blue curveLong Tail

As part of your Information Architecture strategy, it’s worth bearing in mind that you can win traffic by creating more content about more specific subjects – this invariably involves writing pages including content covering longer keyword phrases. As before, don’t continually repeat a long keyword phrase, but write good quality content focusing on your chosen subject.


  1. bhaarat

    Is there any software related to this?

    1. Sam Langdon

      There are a shedload of free online keyword density analysis tools, but if you’re looking for specific recommendations, you could try: Ranks.NL’s keyword density and prominence checker or Just Search’s keyword competition tool (seems to be a bit hit or miss as to whether it works, but it’s rather useful when it does). I’ll no doubt be adding some tools to this site in the near future.

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