Check your text's readability with Flesch Reading Ease, Flesch-Kincaid Grade Level, and Gunning Fog Index. Instant, browser-only, no signup required.
Added May 14, 2026
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Calculates three industry-standard readability scores — Flesch Reading Ease, Flesch-Kincaid Grade Level, and Gunning Fog Index — to tell you how easy your content is to read and which audience it targets.
Flesch RE = 206.835 − 1.015·(words/sentences) − 84.6·(syllables/words) | FK Grade = 0.39·(words/sentences) + 11.8·(syllables/words) − 15.59 | Fog = 0.4·(words/sentences + 100·complex_words/words)
Short sentences and common words produce a high Flesch score (typically 70+) and a low grade level, making it suitable for most readers.
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Flesch Reading Ease ranges from 0 (very difficult) to 100 (very easy). For most web content, aim for 60–70 — this equates to an 8th–9th grade reading level and is comfortable for most adults. Scores of 70–80 suit consumer-facing content; 30–50 is typical for academic or technical writing.
The FK Grade Level estimates the US school grade required to understand the text. A score of 8 means an 8th-grader could follow it. For general marketing or blog content, target grade 6–9. Legal or scientific texts commonly reach grade 12–16.
Gunning Fog penalises long sentences and 'complex' words (3+ syllables). A score under 12 is considered accessible; scores of 17+ approach academic difficulty. Reducing sentence length and replacing jargon with plain language brings the score down.
Syllable counting is the main source of variation — most tools use heuristic algorithms rather than dictionary lookups, and each heuristic handles edge cases (silent e, compound words, proper nouns) differently. Treat the scores as directional guides rather than exact measurements.
Google does not use a readability score as a direct ranking signal, but readability influences dwell time, bounce rate, and social sharing — all of which correlate with rankings. Content that matches your audience's reading level tends to earn more engagement and backlinks.