Readability Score Checker
Paste any text to instantly get your Flesch Reading Ease, Flesch-Kincaid Grade Level, and Gunning Fog Index scores, plus word count, sentence stats, and tips to improve clarity.
Understanding the Readability Score Checker
Readability Score Checker measures how hard your text is to read and reports it on three well-known scales: Flesch Reading Ease, Flesch-Kincaid Grade Level, and the Gunning Fog Index. Paste or type any passage to see each score, along with the underlying counts of words, sentences, syllables, and complex words that drive them. It is for writers, editors, teachers, marketers, and anyone who needs prose to match a target audience or a required reading level. All analysis runs locally in your browser, so your draft is never uploaded, and the scores update as you edit.
How it works
The tool first counts words, sentences, and syllables in your text, then counts "complex" words (those with three or more syllables), since these are the raw inputs every formula shares. Flesch Reading Ease returns a 0-100 score where higher means easier: roughly 60-70 is plain English suited to most readers, 30-50 is difficult, and 90-100 is very easy. Flesch-Kincaid converts the same word and syllable ratios into a US school grade level, so a result of 8 means an average eighth-grader could follow it. The Gunning Fog Index estimates the years of formal education needed on first reading, weighting long sentences and the share of complex words. Because all three respond to sentence length and word length, shorter sentences and simpler words lift every score.
Worked Example
Take a 100-word passage of 5 sentences with 150 syllables and 12 complex words. Words per sentence = 100/5 = 20; syllables per word = 150/100 = 1.5. Flesch Reading Ease = 206.835 - 1.015 x 20 - 84.6 x 1.5 = 206.835 - 20.30 - 126.90 = 59.6, borderline plain English. Flesch-Kincaid Grade = 0.39 x 20 + 11.8 x 1.5 - 15.59 = 7.80 + 17.70 - 15.59 = 9.9, roughly a tenth-grade level. Gunning Fog = 0.4 x (20 + 100 x 12/100) = 0.4 x (20 + 12) = 12.8. Splitting the long sentences in two would push all three toward easier reading.
Tips & Common Mistakes
- Long sentences hurt every score; splitting one 30-word sentence into two often lifts readability more than swapping words.
- The three scales measure different things - Reading Ease is 0-100 (higher is easier) while Fog and Kincaid are grade levels (lower is easier), so do not compare their raw numbers directly.
- For a general audience, many editors aim for a Flesch Reading Ease of 60-70 or a grade level around 8, but match the target to your readers.
- Syllable counting is done by algorithm and can misjudge unusual names, acronyms, or numerals, so treat scores as estimates rather than exact figures.
- These formulas gauge sentence and word length only; they cannot judge whether the content is accurate, well-organized, or logically clear.
- Run the check on a representative sample of a few hundred words; very short snippets can swing wildly from a single long sentence.
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Built and maintained by TopOpenTools · Last updated June 2026.
Frequently Asked Questions
What is Flesch Reading Ease?
Flesch Reading Ease (0–100) measures how easy text is to read. Higher scores mean easier reading: 90–100 is very easy (5th grade), 60–70 is standard (8th–9th grade), and below 30 is very difficult (college graduate level). Most general web content should target a score of 60–70.
What does the Flesch-Kincaid Grade Level mean?
The Flesch-Kincaid Grade Level corresponds to a US school grade level. A score of 8 means an 8th grader can understand it. Most online content targets grade 7–9 for broad accessibility. Academic papers are typically grade 12+.
What is the Gunning Fog Index?
The Gunning Fog Index estimates the years of formal education needed to understand the text on the first reading. A score of 8 means 8th grade level. Scores above 17 are considered "virtually unreadable" for general audiences. Most popular magazines target a score of 8–10.
What readability score should I aim for?
For general blog posts and articles: Flesch Reading Ease 60–70, FK Grade 7–9. For technical documentation: grade 10–12 is acceptable. For children's content: ease score above 80. Marketing copy and emails should aim for ease score 70+ to maximise comprehension.
How accurate is the syllable counting?
The syllable counter uses a heuristic algorithm based on vowel groups, which is approximately 80–90% accurate for English text. Uncommon words, proper nouns, and technical terms may be miscounted. The overall readability score is still a useful directional indicator.