Readability Score Calculator

Formula, tokenization, and interpretation

Flesch Reading Ease is 206.835 − 1.015 × words/sentences − 84.6 × syllables/words. Flesch-Kincaid Grade Level is 0.39 × words/sentences + 11.8 × syllables/words − 15.59. Zero-word input is rejected, and one word or a trailing fragment is treated as at least one sentence.

English words use Latin letters with internal apostrophes; sentence-like segments use terminal punctuation and paragraph breaks. Syllables use a documented vowel-group heuristic with silent-e and consonant-le adjustments. These are estimates, especially for names, abbreviations, numbers, contractions, loanwords, and short samples. Grade level describes formula output, not reader intelligence or writing quality. Limit: 100,000 characters.