SEO Experiments: Keyword Density – Part One

This is the first in hopefully a long line of SEO experiments I will run, which will dig down and let you know what factors actually affect search rankings and what are actually just made up.

One thing I have always wondered about, especially when writing long form copy, is what is the best keyword density on a page.

There is much debate about what the ideal keyword density per page is, and maybe there is not a clear answer to this question given Google’s leanings of late to semantic search. Experts give percentages anywhere from 1% to 10% but most fall between 1% and 3% (such as the popular WordPress SEO tool – Yoast which advises over 0.5% and under 2.5%)

So for this SEO experiment we thought we would test pages at a number of different keyword densities and see which came out on top!

The hypothesis: The optimum keyword density for a page is 2%

The Experiment: To conduct this experiment we created a control page on a new domain and selected a fake (gibberish keyword).

The page consisted of 1000 words of lorem ipsum (not starting with lorem ipsum). The keyword was then added into the page at even intervals at a density of 2%.

This page was then replicated 9 times and the keyword was then inserted in to the varying keyword densities 1-10%.

All pages had a H1 title including the keyword and the keyword was included once in the meta description, meta title and url (with additional differentiators of equal length).

Once live I created a search console submission to get the website indexed by Google.

After a few days I searched the keyword to see if it had indexed.

The Results

The initial results are a little surprising, but this may be just down to some pages indexing before others and the results may need a few more days to settle down.

Here is what I found

The top 3 rankings for keyword density are between 7-9%.

Our 2% keyword density page is 6th out ranked by 1%,3% and 7-9%
I will continue to check this keyword and see if the positions change over the next week or two and report back.