Coleman-Liau Index Calculator
Paste text to get its Coleman-Liau index, a US grade level built from letters per word and sentences per word. Because it counts characters, the score is exact.
How to calculate the Coleman-Liau index
- Paste or type your text into the box.
- Read the index value, which approximates a US grade level.
- Review the character, word and sentence counts, then edit and retest.
Examples
Score a simple sentence
The quick brown fox jumps over the lazy dog.
Index about 3.8
Frequently asked questions
How is the Coleman-Liau index calculated?
It uses L, letters per 100 words, and S, sentences per 100 words. The index is 0.0588 times L minus 0.296 times S minus 15.8.
What does the index number mean?
It approximates the US grade level needed to read the text. An index of 9 suggests a ninth grade reading level.
Why does it count letters instead of syllables?
Coleman and Liau designed it for machine scoring. Counting letters is exact and easy to automate, unlike estimating syllables, so the result is fully determined by the text.
How does it compare to the ARI?
Both are character based and return a US grade. They weight letters and sentences differently, so the two scores are usually close but rarely identical.
Is my text private?
Yes. The score is computed in your browser and nothing is uploaded or stored.
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