Free SEO, AI and GEO toolReadability checker
Paste a text or a page's address: the checker calculates its Flesch reading ease score, the readability formula designed for English, gives the average sentence length and highlights sentences that are too long. A simple text is easier to read, and an AI can more easily reuse one of its sentences as it stands.
How to use the checker
- Paste your text, or the address of the page that contains it.
- Read the score and the level, then the highlighted sentences.
- Shorten the long sentences and run the measurement again.
How the score is calculated
For English, the checker applies the Flesch reading ease formula, created by Rudolf Flesch in 1948: 206.835 − 1.015 × words per sentence − 84.6 × syllables per word. The shorter the sentences and words, the higher the score. Syllables are counted automatically, so the count is approximate. The French, German, Spanish and Italian versions of the checker use the formula specific to each language.
Writing more readably
- One idea per sentence; 15 to 20 words on average is enough.
- Everyday words rather than jargon, or jargon explained.
- The active voice: “We deliver within 48 hours” rather than “Delivery is carried out within 48 hours”.
- The answer first, the details afterwards.
Readability: what it changes for SEO, AI and GEO
Google doesn't present any readability score as a ranking factor. A clear text serves your readers first: they stay, understand and come back. It also serves AI platforms, which readily reuse a clear, complete sentence rather than a muddled paragraph.
Frequently asked questions: readability, SEO, AI and GEO
What is the Flesch reading ease score?
It's a readability score created for English, which combines sentence length and word length. The higher it is, the easier the text is to read. It's the formula the checker applies to English texts; for French, its adaptation by Kandel and Moles is used.
What readability score should I aim for?
For a page aimed at the general public, 60 or more. A technical text can go lower, provided its audience expects it.
How do I calculate the readability of an English text?
With the Flesch reading ease formula: 206.835 − 1.015 × words per sentence − 84.6 × syllables per word. The checker does the calculation for you and shows the sentences that lower the score. Another well-known benchmark, the Flesch-Kincaid grade level, uses the same two measures to express the result as a US school grade.
Does readability matter for Google?
Not as a score. Google looks for pages that are useful and clear for searchers; a readable text contributes to that, without any figure to aim for.
Is my text kept?
No. A pasted text is analysed on your computer and is never sent to iasyo.
