Rix is a simplified readability formula developed by Jonathan Anderson, an Australian teacher, as a variant of Lix. It converts Lix to a grade-level format that teachers and librarians find practical. Rix uses only long words (7+ letters) and sentences—no syllable counting. It correlates highly with Lix and is useful for grades 3 through 12.

Rix = long words / sentences. Long words are words with more than 6 letters (7+ letters), counted after stripping punctuation. We divide the number of long words by the number of sentences. Lower scores indicate easier text; higher scores indicate more difficult text.

For public writing, aim for a Rix score that corresponds to about 8th grade level (typically a score around 3–5). Lower Rix scores indicate text readable by lower grade levels. Rix is useful for materials spanning grades 3 through 12.

Rix is a simplified Lix: Rix = long words / sentences, while Lix uses (words/sentences) + (long words × 100 / words). Rix produces a simpler ratio that Anderson converted to grade levels. Unlike Flesch-Kincaid, Rix uses only letter count—no syllable analysis—making it language-neutral.

Use Rix when you need a simple, grade-level readability measure for educational materials, when categorising books for teachers or librarians, or when you want a formula that correlates with Lix but is easier to interpret. It works well across multiple languages including Danish, Swedish, Norwegian, and Dutch.