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Free Readability Testing Tool.

This Readability Checker will automatically check the readability for any given webpage. To calculate your readability score, enter your URL and the tool will run multiple test.

Readability test

What is Readability?

Readability determines how easy it is for a reader to understand the content of a written text. Based on the complexity, syntax and presentation a algorithm is able to calculate the readability score of a document. This score gives you an estimate of the minimum years of education / grade level needed to understand a specific text.

Readability formulas

This tool will automatically test your content and calculate your readability score based on 6 different readability formulas.

Readability checker

The most popular readability formulas included by this tool:

  • Flesch Kincaid Reading Ease – Formula: 206.835 – 1.015 x (words / sentences) – 84.6 x (syllables / words)
  • Flesch Kincaid Grade Level – Formula: 0.39 x (words / sentences) + 11.8 x (syllables / words) – 15.59
  • Gunning Fog Score – Formula: 0.4 x ( (words / sentences) + 100 x (complex words / words) )
  • Coleman Liau Index – Formula: 5.89 x (characters / words) – 0.3 x (sentences / words) – 15.8
  • SMOG Index – Formula: 1.0430 x sqrt (30 x complex words / sentences ) + 3.1291
  • Automated Readability Index – Formula: 4.71 x (characters / words) + 0.5 x (words / sentences) – 21.43

Flesch Kincaid Reading Ease formula scores

The table below shows you how to interpreted (FRES) score after testing a document with this tool.

ScoreGrade level 
100.00-90.005th gradeVery easy to read.
90.0–80.06th gradeEasy to read.
80.0–70.07th gradeFairly easy to read.
70.0–60.08th & 9th gradePlain English.
60.0–50.010th to 12th gradeFairly difficult to read.
50.0–30.0CollegeDifficult to read.
30.0–0.0College graduateVery difficult to read.

External resource:

To find out more about these formulas and the algorithm behind the concepts, please visit Wikipedia.

How does readability affect SEO?

Readability doesn’t directly influence SEO. That being said, Google does use multiple ranking factors related to user experience like:  Click trough rate (CTR), Bounce rate, Time on page and Returning visitors. If your text is just to hard to understand, you can expect users to leave your page before reading the full content. Hard to read content has a much bigger chance to result in: Higher bounce rates, Lower CTRs and Visitors not engaging with your content (sharing it on social, leaving a comment or linking back to your content). All these factors are very likely to have a negative impact on SEO. 

How to Increase your readability Score?

  • Use simple words.
  • Write short sentences.
  • Use headings and subheadings. 

Readability formulas give you and great indication on how accessible your content is, but you shouldn’t just focus on your calculated score. It’s way more important to connect and write with your audience in mind (these are real people ;-). And depending on your audience and the topics you write about, you should choose the right index and range to use as an indication when testing a document.

Related Tools And APIs

Readability API

You can contact me to get access to the API and add the readability score to your own CMS or application.   


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