Paste your text and see every long sentence colour-coded by severity. Red for 25+ words, teal for 18–25 — with split suggestions so you know exactly where to break them.
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The Flesch Reading Ease formula produces a score from 0 to 100 based on two things: how long your sentences are and how many syllables your words have. Higher scores mean easier to read.
For most online content, aim for 60 or above. Content that is difficult to read tends to have higher bounce rates, which negatively affects rankings.
Average sentence length has the strongest impact. Aim for 15–18 words per sentence on average. Sentences of 30+ words should be the exception, not the norm.
Contractions (you're, it's, we've, don't) reduce syllable count and make text feel more conversational — improving both readability scores and engagement.
Aim for 3–4 sentences per paragraph for online content. Long paragraphs slow readers down and increase cognitive load.
"The software, which was developed in 2019 and has since been updated twelve times, calculates results automatically" is harder to read than "The software calculates results automatically. It was first released in 2019." Same information, better score.
Different content types have different targets. A children's educational site should aim above 80. A general blog performs best between 60 and 70. Professional reports regularly fall below 40, which is normal for their audience. Matching your score to your audience matters more than hitting any specific number.
Alongside the readability score, the Flesch-Kincaid Grade Level formula estimates the US school grade needed to understand your text. A score of 8 means an eighth-grader can read it. For general online content, grade 6–9 is the target range. The editor stats bar above shows your current grade level in real time as you type, so you can track the impact of every edit.
Of the two variables in the Flesch formula — sentence length and syllable count — sentence length has the most dramatic effect on your score. Cutting a 35-word sentence into two sentences of 15 and 20 words improves your score more than replacing a dozen long words with short ones. This is because the formula applies a multiplier of 1.015 to average sentence length, meaning every word you add to a sentence drags the score down proportionally.
The Clarity Highlighter makes this visible. Sentences over 25 words are highlighted in red because they are the strongest candidates for splitting. Sentences of 18–25 words are highlighted in teal as a "watch" zone — they are not necessarily too long, but if your text has many of them, your average will creep up. The split suggestions show you exactly where to break a long sentence based on the nearest conjunction past the midpoint.
Different content types have different readability targets. A children's educational site should aim for a Flesch Reading Ease score above 80. A general blog or news site performs best between 60 and 70. Professional reports and legal documents regularly fall below 40, which is acceptable for their specialist audience. The key is matching your readability score to your audience — a corporate annual report does not need to read like a children's book, and a health information page should not read like a legal contract.
For SEO content, Google's own documentation favours clear, accessible writing. Pages with higher readability scores tend to have lower bounce rates, which over time can support better rankings. This is not a direct ranking factor in isolation, but clear writing keeps readers on the page longer, and engagement is a signal that algorithms measure.
Run-on sentences: Two or more complete thoughts joined without proper punctuation. The fix is usually a full stop at the natural break point. The Clarity Highlighter flags these by word count — if a sentence exceeds 25 words, it is almost always doing the work of two sentences.
Parenthetical overload: Sentences with multiple subordinate clauses nested inside each other. "The software, which was developed in 2019 and has since been updated twelve times across three major versions, calculates results automatically" is technically one sentence but forces the reader to hold too many ideas in memory at once. Split it: "The software calculates results automatically. It was first released in 2019 and has been updated twelve times since."
Polysyllabic word clusters: Multiple long words in sequence ("approximately simultaneously implemented") are hard to process even when each word is individually clear. Replace with shorter alternatives where possible: "roughly introduced at the same time."
What is a good Flesch Reading Ease score? For most online content, aim for 60 or above. This corresponds to "plain English" that a general audience can read without difficulty. Blog posts perform best at 60–70. Content scoring below 50 is considered "fairly difficult" and is appropriate for specialist audiences — academic journals, legal documents, or technical reports. The key is matching your score to your audience rather than chasing a specific number.
How is the Flesch-Kincaid score calculated? The formula uses two variables: average sentence length (words per sentence) and average syllables per word. The calculation is 206.835 − (1.015 × average sentence length) − (84.6 × average syllables per word). Sentence length has the stronger effect because the multiplier (1.015) applies to every word in every sentence. Cutting a 35-word sentence in half improves the score more than replacing a dozen long words with short ones.
Why are long sentences bad for readability? Long sentences force readers to hold multiple ideas in working memory before reaching the full stop — which resolves the meaning. The longer the sentence, the harder the cognitive load. This is especially true for online reading, where readers scan rather than read word by word. The Clarity Highlighter flags sentences over 25 words in red because they are the strongest candidates for splitting at the nearest conjunction.
Can I improve readability without dumbing down my content? Yes. Improving readability means making your writing clearer, not simpler. Replace long words with shorter alternatives where they exist (use → utilise, show → demonstrate). Split long sentences at natural break points. Remove redundant clauses and parenthetical asides. None of these changes reduce intellectual depth — they remove the friction that prevents readers from accessing your ideas.
For detailed walkthroughs with more examples, see our guides How to Improve Your Flesch-Kincaid Score and Ideal Sentence Length for Clarity.