Which readability score is most reliable?

No single score is definitive — each weights sentence length, word length, and vocabulary differently. Flesch-Kincaid Grade Level and Gunning Fog are the most widely cited. Check multiple: if they cluster around the same grade, the estimate is reliable. If they diverge a lot, the text mixes short simple sentences with long hard words (or vice versa).

What grade level should I aim for?

For mass audiences, grade 7-8 (US). Medical / legal plain-language laws often require grade 6-8. Newspapers target grade 9. Academic papers drift grade 12+. Writing below your audience's level rarely loses credibility; writing above it loses readers.

How are syllables counted?

Algorithmically — vowel clusters, silent 'e' detection, common diphthongs. Perfect syllable counting requires a pronouncing dictionary (CMU Pronouncing) which is too large for a browser tool. The heuristic is accurate within ±5% for ordinary English prose — close enough for readability indices that only use integer syllable counts.

Reading Level Checker (Flesch-Kincaid, Gunning Fog, SMOG)

Education & Study· 5 tools

Free reading level checker. Paste any passage and get five industry-standard readability scores — Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog, SMOG Index, and Coleman-Liau Index — plus raw counts of sentences, words, syllables, and complex (polysyllabic) words. Use it to target a specific grade level for blog posts, school essays, or plain-language compliance.

Text to analyze

Sentences

Words

Syllables

104

Complex words

Characters

303

Flesch Reading Ease

-4.3

Very difficult — college graduate

Flesch-Kincaid Grade

16.6

Graduate

Gunning Fog Index

18.9

Graduate

SMOG Index

14.6

College

Coleman-Liau Index

22.0

Graduate

Frequently Asked Questions

References

Flesch-Kincaid formula — original 1975 Navy tech report — DTIC

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Frequently Asked Questions

References and sources

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