Flesch Score Calculator
Paste your text and see at once how easy it reads. With the levers that actually move the score.
Calculate your Flesch score: how easy your text reads
The Flesch reading-ease score measures with one simple formula how easy a text is to read: the shorter the sentences and the shorter the words, the higher the score. 100 means child's play, 0 means legalese. Paste your text above and the calculator scores it live as you write, along with the two levers you can actually pull: average sentence length and syllables per word.
English texts run through Rudolf Flesch's original formula. German texts use the Amstad adaptation, because German words carry more syllables than English ones; scored with the original constants, every German text would grade as difficult. So pick the language first, then paste.
What is a good Flesch score?
For text that should be read rather than filed away, aim for 60 or higher. That is the level of good newspaper writing: short main clauses, everyday words. Ads and newsletters can happily sit above 70. Below 40 reading becomes work, and below 30 the only people still reading are paid to.
Rules of thumb for getting there: under 15 words per sentence on average, no sentence over 25 words, and for every long word the question whether a shorter one would do. The calculator marks your text up like an editor: sentences over 20 words get the highlighter, sentences over 25 the red pen on top, long words a dotted line. You see at a glance where to cut, because that is where the quickest points are.
The prompt for simplifying
The score diagnoses, but it does not rewrite. For that, a ready-made prompt sits under the tool: copy it together with your text into an AI tool of your choice. It locks in the facts and commits the model to the four principles William Zinsser gave every writer in "On Writing Well": as simple as possible, as clear as possible, as brief as possible, as human as possible. Read the result critically, run it through the calculator again, and see in plain numbers what the rewrite achieved.
Frequently asked questions
Does the Flesch score measure whether my text is understandable?
It measures whether your text is easy to decode, not whether it makes sense. A text of short, confused sentences gets a top score. The score is an early-warning system against nested clauses and word monsters, not a substitute for thinking. But as an early-warning system it is surprisingly accurate.
Why does the same text get different scores in German and English?
Because two different formulas do the scoring. English uses Flesch's original (206.835 minus 1.015 times sentence length minus 84.6 times syllables per word), German uses the Amstad adaptation. The scale is the same, but never compare scores across languages, only texts within the same language.
How accurately does the tool count syllables?
It estimates them from vowel groups, like practically every readability tool. For a single word the estimate can be off; across a whole text the errors average out. From about 100 words the score is stable and meaningful.
Does my text end up on a server?
No. The calculator runs entirely in your browser. Nothing is uploaded, stored or read along.