Readability Checker — Free Flesch-Kincaid Score Tool

The Flesch-Kincaid Reading Ease score rates text on a 0–100 scale. Higher scores mean easier reading: 90–100 is Very Easy (simple instructions, children's books), 60–69 is Standard (most web content), and 0–29 is Very Confusing (dense academic or legal writing). The score uses average sentence length and average syllables per word.

Flesch-Kincaid produces two outputs: a 0–100 Reading Ease scale and a US school grade level. The Gunning Fog Index estimates the years of formal education a reader needs to understand the text on first reading. A Fog score above 12 is generally too complex for a broad audience. Use both scores together for a fuller picture.

Most consumer web content performs best at Grade 6–9 (readable by a 12–15 year-old). Blog posts and marketing copy typically aim for Grade 6–8. Technical documentation for professionals can go up to Grade 10–12. For a general audience, a Flesch-Kincaid Grade Level below 9 is a good target.

Sentences with more than 25 words are highlighted in yellow — they are hard to read and often benefit from being split. Sentences with more than 35 words are highlighted in orange — they are very hard and should almost always be broken into shorter sentences. The highlighting appears in the text display below the scores after you click Check Readability.

No. All readability calculations run entirely in your browser using JavaScript. Your text is never uploaded, stored, or transmitted anywhere. You can safely check confidential content, client copy, or unpublished drafts.

The syllable counter uses standard English vowel-group rules with common exceptions for silent-e endings. It is accurate enough for editorial readability guidance. The Flesch-Kincaid and Gunning Fog formulas are designed to tolerate a small margin of syllable-counting error without materially changing the score interpretation.