Readability Checker
Check readability free — Flesch Reading Ease, Flesch-Kincaid grade, Gunning Fog, SMOG, ARI and Coleman-Liau scores plus concrete improvement flags.
About the Readability Checker
Paste any passage and this readability checker scores it with six industry-standard formulas at once: Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog Index, SMOG Index, Automated Readability Index and Coleman-Liau Index. The headline Flesch score is translated into a plain-English reading level, from 'very easy — 5th grade' to 'very difficult — graduate level'.
Beyond raw scores, the tool flags exactly what to fix: it counts sentences longer than 25 words, measures your average sentence length against the recommended maximum of 20, and reports the share of complex words (three or more syllables) with a suggestion to swap in shorter synonyms when that share climbs above 15%.
Readability matters for real outcomes — most web-writing guidance targets a Flesch score of 60+ (roughly 8th-9th grade) because it correlates with comprehension, engagement and even SEO performance. Everything is computed instantly in your browser, so drafts, emails and confidential copy never leave your device.
How to Use the Readability Checker
- 1Paste your text — a few full sentences at minimum for reliable scores.
- 2Read the Flesch Reading Ease headline and its plain-English grade label.
- 3Compare the six formula scores and review the improvement flags.
- 4Edit your text and watch the scores update live; copy the report when done.
Frequently Asked Questions
What is a good Flesch Reading Ease score?
For general audiences aim for 60-70, which corresponds to plain English readable by 13-15 year olds. Marketing copy and mass-market journalism often target 70+; technical or academic writing typically lands at 30-50. Scores run 0-100-plus, with higher meaning easier.
What do the grade-level scores (Flesch-Kincaid, Fog, SMOG) mean?
They estimate the US school grade needed to understand the text on first reading — a score of 8 means an average 8th grader should follow it. The formulas weigh sentence length and word complexity differently, so they rarely agree exactly; treating their range as your answer is more honest than any single number.
How are syllables counted?
With a standard English heuristic: vowel groups are counted, silent trailing e's are handled, and every word counts at least one syllable. It matches dictionary counts for the vast majority of words, and because the same method is applied consistently, comparisons between drafts remain meaningful even when individual words are off by one.
How much text do I need for reliable scores?
At least 100 words is a good rule; SMOG was designed for 30 sentences. Scores over tiny snippets swing wildly because one long sentence dominates the averages. For long documents, checking section by section reveals which parts drag the overall level down.
Do the scores work for languages other than English?
The formulas were calibrated on English, so scores for other languages aren't meaningful on the standard scales. Sentence-length statistics still apply universally, but syllable-based measures like Flesch assume English spelling patterns.
Is my text uploaded anywhere?
No. All counting and scoring happens in your browser with JavaScript — nothing is transmitted, stored or logged, so it's safe to check unpublished manuscripts, legal drafts and internal documents.