The Flesch reading ease score: Why & how to use it

If you have ever run your writing through a readability checker like Yoast SEO, you have probably come across the Flesch reading score. This metric was developed more than 70 years ago and is still one of the most widely used ways to measure how easy your text is to read. But what does it actually mean, and how does it affect your writing for the web?

In this guide, we will explain how the Flesch reading score works, why it became so prominent in publishing and SEO, and how you can use it effectively today. We will also show you where it fits into the Yoast SEO plugin and why we have introduced new readability checks alongside it.

Table of contents

• What is the Flesch reading score?
• How the Flesch reading score is calculated
• Why the Flesch reading score became important
• The Flesch reading score in Yoast SEO
• Why Yoast moved beyond Flesch
• Should you still care about the Flesch reading score?
• How to use the Flesch reading ease score to improve your writing
• Conclusion
• TLDR

What is the Flesch reading score?

The Flesch reading score, also called the Flesch reading ease test, was created by Rudolf Flesch in the 1940s. His goal was simple: to give writers a quick way of checking whether their text was easy to understand. The formula combines three basic elements: sentence length, word length, and syllable count. When these figures are combined into the formula, which I’ll explain in just a moment, they generate a score between 0 and 100.

The highest scores are reserved for the easiest text. For example, a score in the 90s suggests that a typical 11-year-old child should be able to read it without any difficulty. A score of around 60 is closer to plain English that a high school student would be expected to understand. Scores under 30 are considered very difficult and are only really found in academic or legal writing.

Here’s a quick overview of the ranges and what they mean:

Score range	Readability level	Who can understand it
90–100	Very easy	An average 11-year-old student
80–89	Easy	Middle school students
70–79	Fairly easy	Teenagers aged 13–15
60–69	Standard	High school students
50–59	Fairly difficult	College students
30–49	Difficult	University graduates
0–29	Very confusing	Specialists, academics, or experts

Just for fun: this article itself scores around 63 on the Flesch reading score, which puts it in the “standard” range.

How the Flesch reading score is calculated

The formula behind the score looks intimidating, but don’t worry, it is surprisingly straightforward. In fact, it’s only based on two things. The total number of words divided by the total number of sentences, which gives us the ASL or Average Sentence Length, and the total number of syllables divided by the total number of words to get the ASW or Average Syllables per Word. Once we have these figures, we enter them into this formula:

206.835 – (1.015 × ASL) – (84.6 × ASW)

This will give us a score between 0 and 100. The longer your sentences and the more complex your words, the lower your score will be.

Let’s take a quick example by looking at this short text below:

“The cat sat on the mat. The dog barked.”

This has very short words and sentences, so it would score in the 90s, which means it is very easy to read.

Now compare it with:

“The domesticated feline reclined languidly upon the woven floor covering, while the canine produced a resonant vocalization.”

This is essentially the same meaning, but longer words and clauses drop the score dramatically, likely into the 30s.

This example shows why the Flesch reading score works well as a proxy for readability. It rewards writing that is concise and simple with a high score and wags a finger at writing that is dense and complex, ultimately giving it a low score.

Why the Flesch reading score became important

The Flesch reading score spread beyond classrooms into business and publishing because it answered a universal question: Is my writing easy to understand?

By the 1970s, the U.S. Navy was using it to ensure that training manuals were clear for recruits. Later, several U.S. states made it part of their official requirements for insurance documents and consumer contracts. Healthcare organizations also began using it to ensure that patient information was accessible.

When personal computers became common, Microsoft Word added the Flesch reading ease test to its spelling and grammar tools. Suddenly, anyone writing a school essay or business report could get instant feedback on readability. That mainstreamed the score and kept it relevant well into the digital age.

In the world of web writing, readability became even more critical. Online readers scan rather than study text. Research shows they decide within seconds whether a page is worth their time or not. That makes clarity a competitive advantage. Tools that included the Flesch reading score gave web writers a way to benchmark themselves and improve user experience.

The Flesch reading score in Yoast SEO

When Yoast introduced readability checks to the plugin, the Flesch reading score was one of the first tools we built in. We popularized the use of tools to score your content. It gave writers using WordPress an instant way to measure whether their content was accessible to a broad audience. You can still find the Flesch reading ease score inside the plugin today, in the insights tab.

This has helped thousands of users discover that shorter sentences and simpler words often improve how people engage with their content. While the score does not guarantee better rankings, it does contribute to a positive reading experience, which in turn can influence user behavior and SEO outcomes.

Why Yoast moved beyond Flesch

Although the Flesch reading score remains useful, it is not perfect. It only looks at sentence and word length, without considering context, tone, or audience. A blog post aimed at medical professionals may score poorly but still be exactly right for its readers.

That is why we developed additional checks, including word complexity, which evaluates how challenging your vocabulary might be. This allows writers to balance clarity with precision, rather than chasing a single score. In practice, this means you can still use the Flesch reading score as a quick reference, but you should combine it with other insights to get the full picture.

Should you still care about the Flesch reading score?

The Flesch reading score remains a valuable guide for writers who want to make their content more approachable. If your text scores very low, it may be worth shortening sentences or replacing long words with simpler alternatives. But you do not need to obsess over getting a perfect score.

Readability is about more than numbers. Think about your audience, their expectations, and the purpose of your content. Combine the Flesch reading score with other readability signals to create a text that is clear, engaging, and optimized for both humans and search engines.

How to use the Flesch reading ease score to improve your writing

We’ve come to the essential question. How can you use the Flesch score to improve your writing? Well, you write for an audience and know your audience the best. Before writing or editing, consider what kind of texts fit your readers. Do you sell clothes or organize photography workshops? Or do you write for a mom blog or make step-by-step DIYs? Your content should be relatively easy to read in all these cases since you are targeting a broad audience.

However, remember that you do not have to chase a high Flesch reading score at all costs. For example, you may write about complex, specialist topics for a specific, more knowledgeable audience. Or, perhaps you are an academic blogging about your research? It makes sense if the Flesch test produces a lower score in those cases.

Still, whatever your situation is, your text always benefits from concise language. So, if you want to benefit from the feedback the Flesch reading ease score gives you, focus on two things:

1. Shorten your sentences

Too many long sentences make your text difficult to read, while short sentences keep the subject clear. When the sentences in your text are short, you allow your readers to absorb the information in your text. As a result, they don’t need to use all their attention to decipher what you want to say. That is why we advise you to break down long sentences; your text will be much easier to read. 

And please, don’t think that by using short sentences, you will oversimplify your text. Let’s compare two short texts to show you what we mean. First, we have this sentence:

My favorite place to visit during weekends is my grandparents’ house near the lake, where we love to fish and swim, and we often take the boat out on the lake.

Did you find this sentence easy to read? Wasn’t it too lengthy, confusing, and difficult to process? Breaking it into two or more sentences can make it much clearer:

My favorite place to visit during weekends is my grandparents’ house. It’s near the lake, where we love to fish and swim. We also often take the boat out on the lake.

These few short sentences are much easier to read. Yet, you give the same information as in the long sentence, so there is no oversimplifying. Using short sentences keeps the subject clear and lets your readers absorb the information you’re presenting. 

2. Limit your use of difficult words

Words with four or more syllables are considered difficult to read, so try to avoid them where possible. Or try not to use them too much. For example, try words like small instead of minuscule, about instead of approximately, and use instead of utilize. We have the word complexity assessment in Yoast SEO Premium to help you with that.

If you want to reach a broad audience, you should also try to avoid using jargon. If you’re a medical expert, you’re probably familiar with terms like analgesic, intravenous, and oophorectomy. However, keep in mind that most people aren’t. When you can’t find a better alternative, make sure to explain it for users who might not know the word.

Conclusion

The Flesch reading score has been around for decades, and it is not going anywhere. It still offers a quick way to test whether your writing is easy to follow, and it continues to play a role in Yoast SEO. At the same time, the web has moved on, and so have we. By combining the score with modern checks like word complexity, you can create content that is not only readable but also effective in meeting your goals.

So next time you write a blog post, take a look at your Flesch reading score. Use it as a guide, not a rule. The result will be content that your readers and search engines will thank you for.

TLDR

• You should care about your score, but do not chase perfection. Balance readability with your audience’s needs
• The Flesch Reading Score measures how easy a text is to read, using sentence length and word length
• Scores range from 0 to 100: higher is easier. For example, 90–100 is very easy, 60–69 is standard, and 0–29 is very confusing
• It became popular in education, government, and publishing before being integrated into tools like Microsoft Word and SEO platforms
• In Yoast SEO, the Flesch reading score still exists in the Insights tab, but we now also use word complexity to provide more accurate feedback