Compute the Flesch–Kincaid grade level. A score of 8.0 = 8th grade reading level. Compare to a target grade and list sentences above it.
Built and maintained by Paul Clark, Redmoon Software · Last verified · Sources
Use Flesch–Kincaid when your audience is defined by a school grade level — for example, US K-12 educational material, government publications targeted at the "8th grade reading level", or any context where you need a number tied to formal schooling.
Flesch–Kincaid is the grade-level cousin of Flesch Reading Ease — same inputs, different framing. Compared to SMOG it is more lenient (SMOG targets 100% comprehension; FK targets approximate understanding). Compared to Dale–Chall, FK ignores vocabulary; Dale–Chall is better when word familiarity matters.
Flesch-Kincaid Grade Level is the educational counterpart of Flesch Reading Ease, developed for the US Navy in 1975.
The output corresponds to a US school grade level: a score of 8 means an 8th grader should be able to read the passage.
It is widely used by US government agencies and is required for many federal documents.
For general public communication target grade 7–8. For technical documentation, grade 10–12 is acceptable. Avoid going above 14 unless writing for specialists.
Flesch-Kincaid outputs a US grade level instead of a 0–100 score. The two are inversely related: lower ease = higher grade.
FK is more sensitive to syllable count; Fog is more sensitive to complex (3+ syllable) words. Technical text with many compound words usually scores higher on Fog.
Input
Asynchronous request handling requires careful consideration of consistency guarantees.
Output
Flesch–Kincaid Grade Level: 17.4 — Post-graduate.
Eight long words averaging ~3 syllables each, in a single 9-word sentence. The grade level reflects both the syllable density and the unbroken sentence length.
Flesch–Kincaid Grade Level takes the identical two measurements as Reading Ease — average words per sentence and average syllables per word — and recombines them so the output is a US school grade rather than a 0–100 ease score. A result of 8 means the text should be readable by a typical eighth grader.
Because the inputs are the same, the two scores never disagree about which of two documents is harder. They disagree only about how to express it. Reading Ease is easier to communicate to a non-specialist ("we scored 72"); a grade level is easier to act on, because it maps to an audience.
The rescaling is not a simple inversion, so you cannot convert between the two with arithmetic on the output — you need the underlying sentence and syllable averages, which is why both tools compute from the text rather than from each other.
The formula was derived in 1975 for the US Navy, to check that technical manuals matched the reading level of enlisted personnel. That origin is why it produces a grade level at all, and why it became the default in US federal plain-language requirements and in insurance regulation, where many states set a maximum grade level for policy documents.
The caution that comes with that adoption: a grade level is a floor for comprehension, not a guarantee of it. Scoring at grade 8 says the mechanics are within reach of an eighth-grade reader. It says nothing about whether the concepts are, and a document can be simultaneously grade-6 by formula and incomprehensible in substance.
The method behind this tool, so you can check it rather than take it on trust.
Kincaid, J.P., Fishburne, R.P., Rogers, R.L. & Chissom, B.S. (1975). “Derivation of New Readability Formulas for Navy Enlisted Personnel.” US Navy, Research Branch Report 8-75.
Recast Flesch’s score as a US grade level for training material; that recasting is what this tool computes.
Classic 0–100 readability score.
Readability scoresPenalises complex (3+ syllable) words.
Readability scoresHealth & medical text grade level.
Readability scoresNo syllables needed — just characters.