Automated Readability Index (ARI) Definition

The Automated Readability Index (ARI) is an approximate representation of the U.S. grade level needed to comprehend the text.

ARI = (0.5 x ASL) + (4.71 x ALW) - 21.43

Where:

ASL = Average sentence length (the number of words divided by the number of sentences)

ALW = Average number of letters per word (the number of letters divided by the number of words)

The result is a number that corresponds to a numerical U.S. reading grade level.