Readability Checker
Paste your text to get your Flesch Reading Ease score, Flesch-Kincaid grade level, and Gunning Fog index. Long sentences are highlighted directly in the editor.
How to use the readability checker
Paste your text into the editor. Scores appear immediately. Toggle “Highlight long sentences” to see sentences over 25 words marked in yellow and sentences over 35 words marked in red — directly inside the text editor. The list below the scores shows each flagged sentence so you can rewrite them one by one.
How readability scores are calculated
Flesch Reading Ease uses the formula: 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Higher scores mean easier text. The scale runs from 0 (very difficult) to 100 (very easy).
Flesch-Kincaid Grade Level converts the same inputs to a US school grade: 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59.
Gunning Fog adds a complexity penalty for polysyllabic words: 0.4 × [(words ÷ sentences) + 100 × (complex words ÷ words)].
Why readability matters for web content
Content written at the right reading level keeps visitors on the page longer. Studies consistently show that simpler text is read faster, retained better, and trusted more — even by expert readers. Google's quality guidelines emphasise content that serves the reader, and high bounce rates from confusing text are a negative signal. For email, readability directly affects click-through rates.
Frequently asked questions
What is a good Flesch Reading Ease score?
Scores run from 0 (hardest) to 100 (easiest). For most web content, aim for 60–70 — this is 'standard' difficulty, readable by anyone with a secondary school education. Marketing copy often targets 70–80. Academic papers typically score 20–40. Dense legal text often scores below 10. Plain language guidelines for government content usually require a score above 60.
What is the Flesch-Kincaid Grade Level?
It estimates the US school grade level needed to understand the text. Grade 8 means a typical 13–14 year old can read it comfortably. For general web content, grades 7–9 is the sweet spot. Newspapers aim for Grade 6–8. Academic journals typically land at Grade 12–16. The formula uses average sentence length and average syllables per word — longer sentences and longer words both increase the grade.
What is the Gunning Fog Index?
The Gunning Fog index estimates the years of formal education needed to understand a text on first reading. It heavily weights 'complex words' — words with three or more syllables. A score of 12 corresponds roughly to a high school senior. Most popular non-fiction books target a Fog index of 7–10. Technical documentation often runs 12–15. The index is particularly sensitive to jargon — replacing a single long word can move the score noticeably.
Why is my readability score misleading for my text?
Readability formulas are calibrated for continuous prose. They produce unreliable results for: bullet-point lists (few full stops, so sentences appear infinitely long), code snippets (camelCase identifiers skew syllable counts), spreadsheet data, poetry, transcripts with many short sentences, and multilingual text. If your text is mostly structured lists or contains code, the 'unreliable score' warning will appear and scores will be hidden.
How do I improve my readability score?
The two biggest levers are sentence length and word complexity. Aim for an average sentence length of 15–20 words — anything above 25 words consistently damages both scores. Replace multi-syllable words with shorter equivalents where possible ('use' instead of 'utilise', 'help' instead of 'facilitate'). Break compound sentences at conjunctions. The sentence highlight feature in this tool marks sentences over 25 words in yellow and over 35 words in red — those are your highest-priority edits.
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