Flesch-Kincaid Calculator

For most web content, a Flesch Reading Ease score of 60-70 is the standard target. Scores in this range correspond to approximately an 8th-9th grade reading level and are understood by the majority of adult internet users. Scores above 70 indicate even easier text -- appropriate for content targeting a broad audience or people who may not be fluent readers. Scores below 50 indicate content that is difficult for general audiences. Specialist content (legal, medical, academic) may legitimately score below 50 because of the necessary technical vocabulary. Yoast SEO flags content below 60 as needing improvement.

The Flesch-Kincaid Grade Level is a score that approximates the US school grade at which a reader would be able to understand the text. A score of 8 means the text is readable by an average 8th grader -- roughly age 13-14. A score of 12 corresponds to a high school senior. A score above 13 indicates college-level reading difficulty. Most web content guidelines target a grade level of 6-8 for general audiences. The grade level is derived from the same inputs as the Reading Ease score -- average sentence length and average syllables per word -- but uses a different formula that produces a number on a grade scale.

The Flesch Reading Ease formula is: 206.835 minus (1.015 times the average sentence length) minus (84.6 times the average syllables per word). Average sentence length is the total word count divided by the number of sentences. Average syllables per word is the total syllable count divided by the word count. The formula penalises both long sentences and words with many syllables. This is why the two most reliable ways to improve a Flesch score are shortening sentences and replacing multisyllabic words with shorter alternatives.

SEO tools like Yoast include Flesch-Kincaid scores because readability is a proxy for content quality, and content quality affects engagement metrics like time on page and bounce rate. Content that is difficult to read drives readers away faster, which sends negative signals to search engines. Google's quality rater guidelines explicitly reference readability as a signal of content quality. Yoast uses the Flesch Reading Ease score as part of its readability analysis and flags content below 60 as needing improvement. Beyond SEO, many government and public sector organisations require content at a specific grade level to ensure accessibility.

Both scores are produced by the same family of formulas and use the same two inputs: average sentence length and average syllables per word. The Flesch Reading Ease score outputs a number from 0 to 100, where higher means easier -- it was designed to be intuitive for non-specialists. The Flesch-Kincaid Grade Level outputs a number corresponding to a US school grade, which is more useful when communicating a target to writers and editors. A Grade Level of 8 corresponds to a Reading Ease of roughly 60-70. The two scores move in opposite directions: as text becomes harder, Reading Ease goes down and Grade Level goes up.