The Automated Readability Index is a formula that is used to measure and calculate the understandability of a specific text. It is designed to assess how easy or difficult a text is by applying a certain formula. This formula then produces a number, which determines and represents the US grade level required to understand the text.
Formula:
The formula is derived from ratios, which represent the following;
- Word difficulty (number of letters per word)
- Sentence difficulty (number of words per sentence)
Unlike other readability tests, the Automated Readability Index takes into account the total number of characters per word rather than the number of syllables per word. The number output by the formula is the number that determines what grade level is required to comprehend the text.
Here is a breakdown of grade levels in the U.S.:
- 5-6 yrs. old — Kindergarten
- 6-7 yrs. old — First Grade
- 7-8 yrs. old — Second Grade
- 8-9 yrs. old — Third Grade
- 9-10 yrs. old — Fourth Grade
- 10-11 yrs. old — Fifth Grade
- 11-12 yrs. old — Sixth Grade
- 12-13 yrs. old — Seventh Grade
- 13-14 yrs. old — Eighth Grade
- 14-15 yrs. old — Ninth Grade
- 15-16 yrs. old — Tenth Grade
- 16-17 yrs. old — Eleventh grade
- 17-18 yrs. old — Twelfth grade
- 18-22 yrs. old — College
