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Posted in technical writing.

Flesch Score: How readable is your text?

Marvin Blome – .

Learn about the Flesch Index, how to calculate readability, and what scores mean. Improve your writing for better clarity!

Ever read something so complex that it gave you a headache? The Flesch Index helps prevent that! It measures how easy a text is to read. If your text scores high, it’s simple to understand. If it scores low, readers might struggle.

What Is the Flesch Reading Ease Test?

The Flesch Reading Ease Score evaluates how difficult or easy a text is to read. It was developed by Rudolf Flesch in the 1940s. Today, it’s widely used in education, marketing, and web content.

A high score (closer to 100) means the text is simple and clear. A low score (closer to 0) means it’s complex and hard to read.

How to Calculate the Flesch Score

The formula for the Flesch Reading Ease Score is:

Where:

  • ASL (Average Sentence Length) = Total words ÷ Total sentences

  • ASW (Average Syllables per Word) = Total syllables ÷ Total words

The score is based on sentence length and word complexity. Shorter sentences and simpler words give a higher (better) score.

The Flesch Reading Ease formula is based on extensive linguistic research by Rudolf Flesch. The constants in the formula—206.835, 1.015, and 84.6—were derived from statistical analysis of English texts. Flesch analyzed how sentence length (ASL) and word complexity (ASW, measured by syllables per word) affect readability.

  • 206.835 is the base score, representing an ideal readability level before adjustments.

  • 1.015 reflects the impact of longer sentences, which make text harder to read.

  • 84.6 weighs the effect of complex words (more syllables make reading tougher).

These values were fine-tuned through testing to align with real-world readability and ensure the scale effectively predicts text difficulty.

Flesch Score Chart

Here’s how different scores rank in readability:

Score Readability Level Who Can Read It?
90 - 100 Very easy 5th graders and up
80 - 89 Easy 6th graders and up
70 - 79 Fairly easy 7th graders and up
60 - 69 Standard 8th - 9th graders
50 - 59 Fairly difficult High school students and up
30 - 49 Difficult College students and up
0 - 29 Very difficult University graduates only

Why Does the Flesch Score Matter?

  • Improves accessibility: Makes content easier for more people to understand.

  • Boosts engagement: Clearer writing keeps readers interested.

  • Enhances SEO: Search engines favor well-structured, readable content.

How to Improve Your Score

  • Use shorter sentences.

  • Pick simpler words over complex ones.

  • Avoid too many technical terms unless necessary.

  • Break up long paragraphs for better flow.

By keeping your Flesch score high, you make your writing more inviting and effective. Try checking your next piece – how readable is it?

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