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.
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.
Classic 0–100 readability score.
readabilityPenalises complex (3+ syllable) words.
readabilityHealth & medical text grade level.
readabilityNo syllables needed — just characters.