Readability is the measure of how easy a text is to understand. While not a direct ranking factor, readability is related to many user experience metrics, like bounce rate, time on page, and dwell time. In turn, these metrics are related to rankings, so it’s essential to keep readability in mind when creating content.

In this post, I want to explore how the Flesch Reading Ease test can be used to analyze and improve readability, and in what ways it can be useful in terms of SEO.

What is the Flesch Reading Ease score?

The Flesch Reading Ease score measures the readability of a text. Used in communications since the 1940s, the equation created by Rudolf Flesch allows writers to optimize any text’s reading difficulty towards the target audience.

The easier the text is to understand, the higher it is graded on a scale of 0 to 100. The equation is based on the average count of words and syllables per word. 

Working as a consultant to The Associated Press, Flesch came up with a system of evaluating readability for journalists and copywriters to use. He explained his formula in the second chapter of his book, How to Write Plain English

“Multiply the average sentence length by 1.015. Multiply the average word length by 84.6. Add the two numbers. Subtract this sum from 206.835. The balance is your readability score.”

Flesch also provided a table used for interpreting the scores.

Score School level Notes
100.00–90.00 5th grade Very easy to read. Easily understood by an average 11-year-old student.
90.0–80.0 6th grade Easy to read. Conversational English for consumers.
80.0–70.0 7th grade Fairly easy to read.
70.0–60.0 8th & 9th grade Plain English. Easily understood by 13- to 15-year-old students.
60.0–50.0 10th to 12th grade Fairly difficult to read.
50.0–30.0 College Difficult to read.
30.0–0.0 College graduate Very difficult to read. Best understood by university graduates.

Flesch’s working assumption was that the shorter the sentence and the words within, the easier it is to understand. He developed this idea while pursuing a Ph.D. in Library Science at Columbia University. 

Nowadays, the Flesch Reading Ease test is one of the most popular readability measurements. With its influence in the world of news and copywriting, it has proven to produce reliable insight that scales well across various types of text.

And what is the Flesch-Kincaid Grade Level?

In 1975, J. Peter Kincaid was contracted by the U.S. Navy to develop a system for assessing the readability of technical manuals. He modified Flesch’s original equation to present the score as a U.S. grade level. So a text’s score in the Flesch-Kincaid Grade Level reflects the grade level it’s appropriate for. To put it differently, it indicates how many years of education are needed to understand that text.

Don’t confuse these two metrics

While the Flesch-Kincaid Grade Level also uses the average word and syllable count, the score it presents is inverse in comparison to the Flesch Reading Ease test. Since many readability tools test the Flesch-Kincaid Grade Level together with the Flesch Reading Ease, their scores can be confusing. 

With the Flesch-Kincaid Grade Level, the higher the score, the more difficult the text is to read. When it comes to the Flesch Reading Ease test, it’s a low score that indicates reading difficulty.

Optimize your content using the Flesch Reading Ease test

The Flesch Reading Ease test is a great tool to use when you already have a good idea about your audience. 

If you are writing technical content that requires previously acquired information to be understood, you shouldn’t be optimizing towards a score of 80-90. 

On the other hand, if you are hoping for your content to go absolutely viral on social media, a score lower than 30 is a good indicator that you’re doing something wrong. Or that you have great faith in humanity.

For most standard writing, a score of 60-70 is something to aim at. As Rudolf Flesch describes it, a 60-70 score relates to content written in plain English, easily understood by a 9th grader

SEO benefits

Improving readability does not directly relate to ranking in search. However, it is one of the key factors defining the user experience. If a user is satisfied with the content they find, they will stay on the page, spend more time reading, and possibly even share it across social media. 

And the way users behave on a website is most definitely tied to ranking. That’s why adjusting readability to satisfy your audience is always a good idea.

But there’s one more thing to keep in mind.

The smart speaker market is booming, and voice search is gradually becoming a dominant search method. One study predicts that by 2020, 30% of all searches will be done using a device without a screen

If you are hoping to get some of that voice search traffic, be concise and intelligible. Remember that it’s Siri or Alexa who will read your content, so it’s one more obstacle to get your message through.

Readability measurement tools

Obviously, nobody expects you to manually count words and syllables like it’s the fifties. There are free tools available on the web that can help you with that. 

Tools like or will analyze your content in seconds and provide the Flesch and Flesch-Kincaid scores as well as various other readability metrics. You can use them both to review the text you’re currently writing, or to analyze content that’s already published by submitting a URL.

To give you a solid example, I used the test on the article you are currently reading. Unless you were skipping through, you should have a general idea about its’ readability, so you can compare how it feels to you with the score it gets.  

I got a score of 61 on the Flesch Reading Ease test and 7.8 on the Flesch-Kincaid Grade Level, which makes me quite happy! I am sure that you are capable of reading something much more complex, but I wanted to find the right balance between engagement and information.

What if your score is too low?

If the test suggests that your audience will have a hard time reading your content, there are two simple steps to consider which can improve readability: 

  1. Break up long sentences and transform them into several shorter ones. In many cases, subordinate clauses can work well on their own. Don’t be afraid of using too many short sentences. Alternating between longer and shorter sentences improves the text’s readability.
  2. Consider using shorter synonyms. Sometimes, using too many complex, multi-syllable words can obscure the overall meaning. In essence, any text should communicate first and foremost. I’m not suggesting to exclusively write with monosyllables – there’s a balance to be found with everything.

Just remember, the test’s results are open to interpretation. Set your own goals

If you struggle to properly explore the topic at hand, and get a good Flesch grade at the same time, remember: it’s just an arbitrary test. Your idea is the most important, so convey it to your audience any way that you feel will work.

If you want to know more about how you can use the Flesch Reading Ease test, check out “How to Make Your Content Read Better in 3 Steps“: