The 6 most accurate keyword difficulty tools

Do keyword research tools actually work?

We use them every day. Our basis? Faith. Has anyone organically measured how well keyword research tools report on the organic difficulty of a given keyword?

We’ve done just that. So, let’s stop with the chit-chat and get to the point.

While Moz wins the top position as a keyword research tool, know that any keyword research tool with organic difficulty functionality will give you an advantage over making a coin toss.

The Pearson Correlation Coefficient

In order to understand the relation between two variables, out first step is to scatter a plot chart.

Below is the scatter plot chart of 50 keyword rankings compared to their corresponding Moz organic difficulty scores?
Ingenious Folks blog - Keyword Rankings

This chart is fine; however, it’s not very scientific. This is when the Pearson Correlation Coefficient (PCC) comes into play.
Ingenious Folks blog - PCC

There’s at least one expert in every business. Many businesses have more than one expert to draw expertise from. They are the most valuable assets that can be used from a content-marketing point of view.

Let’s use the following table from to interpret the PCC score for each tool:
Ingenious Folks blog - PCC Score

In order of performance:

  1. Moz

Ingenious Folks blog - Moz Performance
There is a tight grouping of results relative to the regression line with a few moderate outliers.
Ingenious Folks blog - Moz Organic Difficulty Predictions

Moz was able to generate 100% matched keywords out of the 50 keywords studied.

  1. Spyfu

Ingenious Folks blog - Spyfu
SpyFu shows a fair cluster among low effort keywords, and some moderate outliers within keywords with high difficulty.
Ingenious Folks blog - Spyfu Organic Difficulty Predictability

With 1.75 weaker PCC, SpyFu came in second. 40 out of 50 keywords were matched.

  1. SEMrush

Ingenious Folks blog - SEMrush PCC
The PCC is very sensitive to outliers, which pushes SEMrush’s score down to third.
Ingenious Folks blog - SEMrush Score

  1. KWFinder

Ingenious Folks blog - KWFinder
With numerous strong outliers, KWFinder comes right after SEMrush with a score of 360.
Ingenious Folks blog - KWFinder ODP

The KWFinder tool had a 100% match rate without any trouble digging around for the data.

  1. Ahrefs

Ingenious Folks blog - Athrefs Keyword

Barely passing the weak relationship threshold, Ahrefs stands fifth by a large margin at 316.
Ingenious Folks blog - Ahrefs ODP
The tool seems to be reliable with low difficulty scores.

  1. Google Keyword Planner Tool

Ingenious Folks blog - Google Keywords Planner Tool
Some SEO companies still use the paid competition figures from Google’s Keyword Planner Tool. There is no linear relationship between two variables, as you can see from the scatter plot.
Ingenious Folks blog - Google Keyword Planner Tool ODP

Agencies that still use KPT for organic research (you know who you are!) — Let this be as a warning: you need to evolve.

If you need an expertise in Keyword search, feel free to contact us.

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