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Both scores originate from the US Department of Defense readability spec that Rudolf Flesch and J. Peter Kincaid co-authored in the 1970s. plainlanguage.gov: readability tools.
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Readability: Flesch Reading Ease and Flesch-Kincaid
The two readability scores the counter reports, where they came from, and what to make of them.
Flesch Reading Ease
Formula: 206.835 - 1.015 * (words / sentences) - 84.6 * (syllables / words). Output is a 0 to 100 score. Higher is easier. Readeru2019s Digest scores around 65. The Bible King James Version scores around 70. Legal text scores around 30.
Flesch-Kincaid Grade Level
Formula: 0.39 * (words / sentences) + 11.8 * (syllables / words) - 15.59. Output is a US grade level. Grade 8 is the newspaper target. Grade 12 to 14 is college-level academic prose. Grade 20 is dense legal or scientific writing.
What to do with the number
- Marketing web copy: aim Grade 6 to 8 (Reading Ease 60 to 80).
- News: Grade 8 (Reading Ease 60 to 70).
- Long-form editorial: Grade 10 to 12 (Reading Ease 50 to 60).
- Academic: Grade 12 to 16 (Reading Ease 30 to 50).
- Legal / contracts: Grade 16+ (Reading Ease under 30).
How syllables are counted
The counter uses a regex heuristic: split on vowel groups, subtract silent-e endings, apply a minimum of 1 per word. Accurate enough for readability scoring, not accurate enough for poetry meter analysis.
See it live
Paste your text into the homepage counter and open the advanced stats panel. Both scores are computed live on every keystroke.