Readability Score Checker
Clear writing reaches more people. Our Readability Score Checker analyzes your text using four industry-standard formulas — Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog Index, and Coleman-Liau Index — to tell you exactly how accessible your writing is. Each score approaches readability from a different angle, measuring factors like average sentence length, syllable density, and word complexity. The tool displays a grade level estimate so you can see whether your text is appropriate for your intended audience. For writers who want to improve, the AI-powered suggestion feature provides actionable tips on how to simplify complex sentences, replace difficult vocabulary, and lower your grade level without sacrificing meaning.
How to use
Paste your text to see readability scores and grade level in real-time.
Uses 4 industry-standard formulas.
- check_circle Flesch-Kincaid Reading Ease & Grade
- check_circle Gunning Fog & Coleman-Liau
- check_circle AI-powered improvement tips
What is a Readability Score Checker?
Readability formulas quantify two things that make text hard to process: long sentences and polysyllabic words. The Flesch-Kincaid Grade Level and Gunning Fog Index both combine average sentence length with a measure of word complexity — Flesch-Kincaid uses average syllables per word, while Gunning Fog counts words of three or more syllables as "complex." A grade level of 12 means a high-school senior can follow it; a grade level of 16 means most readers will struggle. Research on web content consistently finds that targeting grade 7–9 maximises comprehension across the broadest audience, including readers who have the knowledge but are skimming on a phone.
For a full explanation of what each score means and how to use the results, visit our guide at https://usertools.app/guides/what-is-a-readability-score. To improve your scores in practice, start with the Word Counter to check whether over-long articles are padding sentence averages upward, then apply the Text Formatter to break run-on constructions into cleaner, shorter units before re-running your analysis.
When should you use it?
- check_circle Content marketers ensuring blog posts are accessible to a general audience at a 7th-8th grade level
- check_circle Technical writers checking whether documentation is appropriate for its intended reader skill level
- check_circle Teachers and professors assessing whether assignment materials match student reading ability
- check_circle Healthcare communicators verifying patient-facing materials meet health literacy guidelines
- check_circle Legal professionals simplifying contracts and terms of service for consumer readability
- check_circle Non-native English speakers checking whether their writing is clear and appropriately simple
How it works
The tool calculates four readability scores, each using a different mathematical formula. Flesch Reading Ease uses average sentence length and average syllables per word to produce a score from 0 to 100 — higher scores indicate easier reading. Flesch-Kincaid Grade Level uses the same inputs but maps them to a US school grade level. Gunning Fog counts 'complex words' (three or more syllables) and combines that with average sentence length. Coleman-Liau is unique in that it uses character count rather than syllable count, making it more reliable for technical text.
Syllable counting is performed using a vowel-group heuristic: the tool scans each word for consecutive vowel sequences and counts each group as one syllable, with adjustments for silent-e endings and other common English patterns. While no algorithmic syllable counter is perfect for every word, the aggregate scores across a full text are highly reliable.
The AI suggestion feature sends your text to a language model with specific instructions to identify the most impactful readability improvements. It looks for overly long sentences, passive voice, jargon, and multi-syllable words that could be replaced with simpler alternatives, then provides concrete revision suggestions.