Coleman Liau Index

The Coleman–Liau Readability Formula (also known as The Coleman–Liau Index) is a readability assessment test designed by linguists Meri Coleman and T. L. Liau to approximate the usability of a text.

Coleman said he created the formula as one of the many ways to help the U.S. Office of Education calibrate the readability of all textbooks for the public school system. Like other popular readability formulas, the Coleman–Liau Index approximates a U.S. grade level to understand the text.

Similar to the Automated Readability Index, but unlike most of the other grade-level predictors, the Coleman–Liau relies on characters instead of syllables per word. Instead of using syllable/word and sentence length indices, Meri Coleman and T. L. Liau believed that computerized assessments understand characters more easily and accurately than counting syllables and sentence length.


Ranking is similar to the Gunning Flog Index:

Fog Index Reading level by grade
20 Post graduate Plus
19 Post graduate Plus
18 Post graduate
17 College graduate
16 College senior
15 College junior
14 College sophomore
13 College freshman
12 High school senior
11 High school junior
10 High school sophomore
9 High school freshman
8 Eighth grade
7 Seventh grade
6 Sixth grade

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