Readability Scores (Flesch-Kincaid)
Flesch-Kincaid Grade Level and Flesch Reading Ease for any text.
Example
You enter
- Text to score (paste or type a paragraph) The quick brown fox jumps over the lazy dog. This sentence contains words of varying length. Some are short. Others are considerably longer. The readability formulas were developed for the United States Navy by Kincaid and colleagues in 1975. Their goal was to estimate the grade level needed to read a passage of running prose. The formulas remain widely used today by educators and writers.
You get
- Sentences 7
- Words 66
Checked against published worked examples from: Kincaid et al. (1975), Flesch (1948), both public-domain U.S. government / journal...
Details, formula, and sources
ScopeWord / sentence / syllable counts. Public-domain federal formula.
Formula or tableFlesch-Kincaid Grade Level: 0.39 * (words/sentences) + 11.8 * (syllables/words) - 15.59. Flesch Reading Ease: 206.835 - 1.015 * (words/sentences) - 84.6 * (syllables/words).
Source and editionKincaid, Fishburne, Rogers, and Chissom, 'Derivation of New Readability Formulas for Navy Enlisted Personnel,' Naval Technical Training Command Research Branch Report 8-75 (1975). Flesch, 'A New Readability Yardstick,' Journal of Applied Psychology 32:3 (1948).
Free accessPublic-domain U.S. government publication. Free at dtic.mil (DTIC report search).
What governsEstimate only. Readability formulas and similar metrics are derived from a representative population and have known edge-case noise. The classroom teacher governs final text selection, grade placement, and assessment decisions.
API field namestext, sentences, words
- Sentence boundary split on a period / question mark / exclamation followed by whitespaceconvention; abbreviations like 'Mr.' will over-segment
- Word boundary any maximal run of letters; apostrophes preserved internallyconvention
- Syllable count vowel-cluster heuristic, floor of 1 per worddeterministic approximation; differs from a dictionary count by ~5%
- Validity range running prose of >= 50 wordsKincaid 1975 Section 3 (shorter passages produce noisier scores)