Flesch-Kincaid Grade Level

A readability formula that estimates the U.S. school grade level required to comfortably read a given English text, based on average sentence length and average syllables per word. Developed for the U.S. Navy in 1975 by Rudolf Flesch and J. Peter Kincaid, the formula is widely used in word processors, plain-language guidance, and accessibility tools to gauge how demanding a document is. A score of 8 means the text is readable by an eighth-grader. Flesch-Kincaid is a rough heuristic that only considers surface features (it cannot judge vocabulary familiarity, concept difficulty, or cultural context), so it should be treated as a triage tool rather than a guarantee of plain language. Plain-language guidance typically recommends aiming for grade 8 or lower for general audiences.