ARI uses characters per word and words per sentence to produce a U.S. grade level for your text.
The Automated Readability Index was developed in 1967 for the US Air Force as a fast readability check.
Like Coleman-Liau it relies on character counts, but it also factors in average sentence length directly.
ARI is particularly suitable for evaluating technical and instructional material.
Both rely on characters per word, but ARI also uses average sentence length while Coleman-Liau uses sentences per 100 words. They typically produce similar grade levels.
ARI was developed for the US Air Force in 1967, originally to grade training material.
Classic 0–100 readability score.
readabilityU.S. grade level for your text.
readabilityPenalises complex (3+ syllable) words.
readabilityHealth & medical text grade level.