Estimate the U.S. grade level needed to understand the text using character and word counts. Fast and reliable.
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The Coleman-Liau index was designed in 1975 specifically for automated computing — it requires no syllable counting.
It uses characters per word and sentences per 100 words to estimate US grade level.
Because it only needs character counts, it generalises better across languages with regular spelling.
Characters are easier to count programmatically and don't require language-specific syllable rules. This makes Coleman-Liau a popular choice for automated tools.
Yes — Coleman-Liau correlates well with cloze test scores, the gold standard of readability research.
Classic 0–100 readability score.
readabilityU.S. grade level for your text.
readabilityPenalises complex (3+ syllable) words.
readabilityHealth & medical text grade level.