Readability Checker
Analyze how easy your writing is to read using three industry-standard readability formulas.
About the Three Readability Formulas
A single readability score only tells part of the story. Each formula below measures a different aspect of how demanding your writing is on the reader.
Flesch Reading Ease
Developed by Rudolf Flesch in 1948, this is the most widely used readability formula. It produces a score between 0 and 100 based on average sentence length and average number of syllables per word. Higher is easier. A score of 60–70 works well for general audiences. Scores above 80 feel conversational. Below 50 tends toward the dense or academic.
Flesch-Kincaid Grade Level
This formula uses the same two variables as Flesch Reading Ease but rearranges them to map directly to a U.S. school grade level. A result of 8 means an eighth-grader should be able to read it comfortably. Most newspapers target a grade level between 7 and 9. Academic papers often land between 12 and 16.
Gunning Fog Index
Created by Robert Gunning in 1952, the Fog Index estimates how many years of formal education a reader needs to understand your writing on the first pass. It factors in sentence length and the proportion of "complex" words (those with three or more syllables). A fog index of 12 corresponds roughly to a high school senior. Anything above 17 is considered extremely difficult.
Using the Scores Together
The three scores will generally agree on whether your writing is easy or hard. Where they diverge is useful. A high Fog Index alongside a moderate Flesch score often means you have long polysyllabic words even though your sentences are short. A low Flesch-Kincaid grade alongside a high Fog Index suggests complex vocabulary buried in otherwise simple sentence structures.
If certain passages still feel heavy, a Sentence Checker can help you tighten structure at the sentence level. For vocabulary that keeps inflating your syllable counts, the Vocabulary Repetition Crusher can surface overused complex words.
If the issue runs deeper than sentence length or word choice, an AI text humanizer can reshape the content to read more naturally without losing its meaning.