Flesch-Kincaid Calculator
The Flesch-Kincaid Grade Level is a widely used readability formula. It returns a US school grade: a score of 8.2 means about an 8th-grade reading level. Higher means harder.
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What the Flesch-Kincaid Grade Level measures
The Flesch-Kincaid Grade Level was derived in 1975 by J. Peter Kincaid, Robert P. Fishburne Jr., Richard L. Rogers and Brad S. Chissom for the US Navy (Kincaid et al., Research Branch Report 8-75). They tested 531 enlisted personnel on 18 passages from training manuals. Microsoft Word can show the score in its readability statistics, next to Flesch Reading Ease.
The formula combines two measures: average sentence length and average syllables per word. It turns them into a single grade-level number.
How to interpret your Flesch-Kincaid score
| Grade | Label on this calculator |
|---|---|
| Up to 5 | Elementary |
| 6–8 | Middle school |
| 9–12 | High school |
| 13–16 | College |
| 17+ | Graduate |
Microsoft suggests a grade of around 7.0 to 8.0 for most documents. No US federal rule sets a Flesch-Kincaid grade, so pick the grade your readers need.
When to use Flesch-Kincaid
- Web content — a quick check that a page suits its readers. Google lists no reading-level ranking factor.
- Government documents — plain-language work under the US Plain Writing Act, which sets no grade level.
- Educational materials matched to a specific grade level.
- Marketing copy for a broad audience.
- Internal documents being rewritten for a non-specialist audience.
How the Flesch-Kincaid Grade Level is calculated
In plain English: multiply the average sentence length by 0.39, multiply the average syllables per word by 11.8, add the two, and subtract 15.59.
Both terms matter. In a 20-word sentence, swapping two 3-syllable words for 1-syllable words lowers the grade by about 2.4. Splitting the sentence into two 10-word sentences lowers it by about 3.9.
Flesch-Kincaid vs other readability formulas
Flesch-Kincaid Grade Level and Flesch Reading Ease share the same inputs but weight them differently. Reading Ease is a 0 to 100 score (higher is easier), Grade Level is a US school grade (lower is easier). They usually move together, so you rarely need both.
Gunning Fog uses average sentence length and the percentage of "complex" words (3+ syllables) instead of total syllables. It counts a three-syllable word and a six-syllable word the same.
SMOG counts complex words per sentence. A 2013 review found it best suited to health care applications, and McLaughlin's method uses 30 sentences. Coleman-Liau and ARI count letters instead of syllables.
Frequently asked questions
What is a good Flesch-Kincaid score?
It depends on your readers. Microsoft suggests a grade of around 7.0 to 8.0 for most documents. No US federal rule sets a grade.
What Flesch-Kincaid score does the US government require?
None. The Plain Writing Act of 2010 tells federal agencies to write in plain language. It sets no grade level and names no formula.
What is the difference between Flesch-Kincaid and Flesch Reading Ease?
Flesch-Kincaid Grade Level returns a US school grade (8.2 = 8th grade). Flesch Reading Ease returns a 0 to 100 score where higher means easier. Both use sentence length and syllables per word, with different weights.
Is Flesch-Kincaid accurate for technical writing?
Flesch-Kincaid counts sentence length and syllables per word. Technical writing often has long words, so its grade tends to be high. The score is still useful for comparing two drafts of the same document.
How do I lower my Flesch-Kincaid score?
Split long sentences and swap long words for shorter ones. Both terms matter: halving a 20-word sentence lowers the grade by about 3.9, and removing four syllables from it lowers the grade by about 2.4.
Does Flesch-Kincaid work for languages other than English?
Not directly. The formula was built from tests of US Navy personnel reading English training manuals. Other languages have their own formulas.