Word counter with reading time and readability scores

What is counted

A word is a run of letters or digits, joined across apostrophes, hyphens and inner full stops (so don’t, well-known, U.S. and 3.14 each count once); each Chinese or Japanese character counts as one word, as word processors do. A sentence ends at . ! ? or … followed by a space or the end of the text, except after common abbreviations (Mr., Dr., e.g., etc.) and single initials. A paragraph is a non-empty line. Characters are Unicode code points, with and without white space.

Reading time is words ÷ your reading speed; speaking time uses 183 words per minute, Brysbaert’s average for reading aloud.

Readability formulas

With W words, S sentences, Y syllables, L letters, P words of three or more syllables and C “complex” words (three or more syllables, not counting proper nouns, hyphenated compounds, or an -es, -ed or -ing ending):

• Flesch Reading Ease = 206.835 − 1.015 (W/S) − 84.6 (Y/W)
• Flesch–Kincaid grade = 0.39 (W/S) + 11.8 (Y/W) − 15.59
• Gunning Fog index = 0.4 [(W/S) + 100 (C/W)]
• SMOG grade = 1.0430 √(P × 30/S) + 3.1291
• Coleman–Liau index = 0.0588 L′ − 0.296 S′ − 15.8, where L′ is letters and S′ sentences per 100 words

Worked example: Wikipedia’s Flesch–Kincaid sample sentence, shown above, has 13 words, 1 sentence and 24 syllables, giving Reading Ease 37.5 and grade 11.3; “The cat sat on the mat.” scores 116.1.

Limits

Syllables are estimated with English spelling rules (vowel groups, silent final e, a short exception list); the estimate matches dictionary counts for about nine common words in ten, so scores can differ slightly from other tools. The formulas were fitted to English prose of 100 words or more and say nothing about meaning, layout or audience; for other languages the counts are still useful but the scores are not. SMOG was calibrated on 30-sentence samples.

References

• Flesch, R. (1948). A new readability yardstick. Journal of Applied Psychology, 32(3), 221–233
• Kincaid, J. P., et al. (1975). Derivation of new readability formulas for Navy enlisted personnel (Research Branch Report 8-75)
• McLaughlin, G. H. (1969). SMOG grading: A new readability formula. Journal of Reading, 12(8), 639–646
• Coleman, M., & Liau, T. L. (1975). A computer readability formula designed for machine scoring. Journal of Applied Psychology, 60(2), 283–284
• Gunning fog index (formula and history)
• Flesch–Kincaid readability tests (worked example)
• Brysbaert, M. (2019). How many words do we read per minute? Journal of Memory and Language, 109, 104047