The Automated Readability Index (ARI) is a readability test designed to gauge the understandability of a text. Like the Flesch-Kincaid Grade Level, Gunning-Fog Index, SMOG Index, Fry Readability Formula, and Coleman-Liau Index, its output is an approximate representation of the U.S. grade level needed to comprehend the text.
Unlike the other indices, the ARI, along with the Coleman-Liau, relies on a factor of characters per word, instead of the usual syllables per word. Although opinion varies on its accuracy as compared to the syllables/word and complex words indices, characters/word is often easier to calculate, as the number of characters is more readily and accurately counted by computer programs than syllables.
Formula
To calculate the Automated Readability Index:
- Divide the number of characters by the number of words, and multiply by 4.71.
- Divide the number of words by the number of sentences, and multiply by 0.5.
- Add #1 and #2 together, and subtract 21.43.
The output approximates the minimum grade level needed to comprehend the text. A score of 8.2, for instance, should easily be understood by the average 14-year-old.
US School Grade and Ages
| Level/Grade | Typical age |
|---|---|
| Preschool | |
| Various optional programs, such as Head Start | Under 6 |
| Pre-Kindergarten | 4-5 |
| Kindergarten | 5-6 |
| Elementary School | |
| 1st Grade | 6–7 |
| 2nd Grade | 7–8 |
| 3rd Grade | 8–9 |
| 4th Grade | 9–10 |
| 5th Grade | 10–11 |
| Middle School | |
| 6th Grade | 11–12 |
| 7th Grade | 12–13 |
| 8th Grade | 13–14 |
| High school | |
| 9th Grade(senior 1) (Freshman) | 14-15 |
| 10th Grade (senior 2) (Sophomore) | 15-16 |
| 11th Grade (senior 3) (Junior) | 16-17 |
| 12th Grade (senior 4) (Senior) | 17–18 |
| Post-secondary education | |
| Tertiary education (College or University) | ages vary (usually four years, referred to as Freshman, Sophomore, Junior and Senior years) |
| Vocational education | ages vary |
| Graduate education | |
| Adult education | |
External links
- Online readability tests - finds ARI and other indices, suggestions how to improve readability
- Readability calculators - six readability statistics