What’s behind the Flesch Reading Ease Test?

Ever dipped your toes into the world of readability? Then you’ll likely have come across the Flesch Reading Ease Test. It’s the industry standard for measuring how easy (or not) a text is for someone to read. It’s ironic that, with such a complex name, it’d probably fail its own test. But the theory behind it is pretty simple.
Fergal McGovern

CEO & Founder

4 min read

A (Very) Short History of the Flesch Reading Ease Test

The test itself was the work of Rudolf Flesch. A writing and readability expert, Flesch was a key player in the Plain English Movement of the late ‘40s. He published many seminal books about the importance of plain language and clear writing. Flesch developed his readability formula in 1948. And a few decades later, he teamed up with J Peter Kincaid to develop the Flesch-Kincaid Grade Level Test.

Keeping score…

So what do the scores within the Flesch Reading Ease Test actually mean? There’s a complex formula working behind the scenes. But there’s really only one thing you need to remember. The higher the score, the easier the text is to understand.


US School level




5th grade

Very easy to read. Easily understood by an average 11-year old student

Harry Potter and the Sorcerer’s Stone, JK Rowling


6th grade

Easy to read. Conversational English for consumers.

The Lord of the Rings JRR Tolkein


7th grade

Fairly easy to read.

Harry Potter and the Deathly Hallows, JK Rowling


8th & 9th grade

Plain English. Easily understood by

The Tipping Point,
Malcolm Gladwell


10th to 12th grade

Fairly difficult to read.

Moby Dick, Herman Melville



Difficult to read.

Academic paper on chess


College graduate

Very difficult to read. Best understood by university graduates.

The Affordable Care Act

Flesch, Rudolf. “How to Write Plain English”. University of Canterbury and examples based on research by VisibleThread and Shane Snow

We mentioned the Flesch-Kincaid Grade Level Test earlier. This was developed after the Flesch Reading Ease Test. It matches the readability scores up with the US grade level of education that the reader would need to understand that text.

Why score content for readability?

Let’s take a step back and think of the bigger picture. Why do we go to such trouble to score content? Or make it readable? Simply because writing in plain language allows you to reach as many people as possible. Having a good readability score can also dramatically improve user experience – think of the negative impact jargon-laden banking terms or complex Medicare documentation can have. Finally, it makes sense, and it’s also the law. The Plain Writing Act came into force in 2010. It requires that federal agencies use clear government communication that the public can understand and use. And while not mandated legally, regulators such as the SEC strongly advocate for clear language.

Experts suggest aiming for a score of 60 or higher when writing for the average American. Referring back to our scoreboard, we’re aiming for a Moby Dick level of understanding. That might sound easy. Moby Dick is a pretty challenging read, so firms should be able to pitch content at this level, right? We found the opposite to be true. Our research uncovered many industries creating content that is way above this benchmark. These include:

  • Asset management
  • US healthcare industry (specifically, Medicare documents)
  • Retail banking
  • Insurance industry
  • Government agencies

You can see all of our research reports here.

And the results are sobering. Failure to communicate clearly erodes trust amongst consumers, and significantly adds to business costs when customers call for clarity.

“But all our customers are well-educated…”

Many organizations fall into the trap of believing that, as their industry deals with complex subject matter, communications must be difficult to understand. It’s an inevitable consequence of healthcare/finance / <<insert your own “complex industry” here>>. Or worse, they believe that their customers are too smart for plain language. That they’ll feel “spoken down” to. In fact, the opposite is true. The UK’s government website says it best: “the more educated a person is, and the more specialist their knowledge, the more they want it in plain English.” Make no mistake – it is possible, and crucial, to make content from all industries accessible to everyone. For so many reasons:

  • We’re all pressured for time, and complex communications add to our cognitive load.
  • In complex industries such as healthcare and finance, it’s even more critical that readers understand the content. The subject matter is too important to miss any details.
  • Communicating in plain language makes it less likely that customers will have follow-up questions. That saves time and money for both the business and the customer.

Flesch is important… but it’s no silver bullet

Let’s not forget that the Flesch Reading Ease Test is just one measure of readability. It is, by no means, the only thing to check for in your content. Other crucial factors to consider are:

  • Long sentence density
  • Overuse of passive voice (much harder to process than active voice)
  • Pronoun density
  • Complex word density
  • Use of jargon and industry acronyms
  • Overuse of institutional language

Our VT Insights platform scans content for readability and also flags instances of the above. Writers and subject matter experts can score their own written content, ensuring that communications across the organization are clear, coherent, and consistent.

But don’t forget the importance of great subject matter – something that no product or test will account for. Just because something is more readable doesn’t make it better or more appropriate. Refer back to our scoreboard from earlier on in the blog. Harry Potter and the Sorcerer’s Stone is pitched at a score of 90-100. Whereas the academic paper on chess is readable by college students, with a score of 30-50. That actually makes sense, more or less. It would be strange if a Young Adult Fiction (YA) novel was pitched at college level. Or an academic paper for 5th graders. However, health insurers creating Medicare content that’s harder to read than Moby Dick does not make sense.

It has been over 70 years since Flesch developed his formula, it’s time to do better.


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