What Is the Flesch-Kincaid Readability Score?
Flesch-Kincaid Grade Level = 0.39 × (total words / total sentences) + 11.8 × (total syllables / total words) - 15.59. A score of 8 means an 8th grader can understand it. Most tech docs should target grade 8-10.
The Two Formulas
There are two Flesch-Kincaid metrics that use the same inputs but produce different scales:
Flesch-Kincaid Grade Level
FK Grade = 0.39 * (words / sentences) + 11.8 * (syllables / words) - 15.59Maps directly to a U.S. school grade. A score of 8.2 means an 8th grader can understand the text.
Flesch Reading Ease
Reading Ease = 206.835 - 1.015 * (words / sentences) - 84.6 * (syllables / words)Produces a score from 0-100 where higher = easier. 60-70 is considered plain English.
Worked Example
Consider this passage: "The cat sat on the mat. It was a good day."
- Words: 11
- Sentences: 2
- Syllables: 11 (the=1, cat=1, sat=1, on=1, the=1, mat=1, it=1, was=1, a=1, good=1, day=1)
FK Grade = 0.39 × (11/2) + 11.8 × (11/11) - 15.59 = 0.39 × 5.5 + 11.8 × 1.0 - 15.59 = 2.145 + 11.8 - 15.59 = -1.6
A negative score means the text is extremely simple -- suitable for very early readers.
Target Scores by Content Type
| Content Type | FK Grade | Reading Ease |
|---|---|---|
| Marketing copy | 5-7 | 70-80 |
| Blog posts | 6-8 | 60-70 |
| Technical documentation | 8-10 | 50-60 |
| Academic papers | 12-16 | 30-50 |
| Legal documents | 16+ | 10-30 |
How to Improve Your Score
- Shorter sentences: Break sentences over 20 words into two.
- Simpler words: Use "use" instead of "utilize," "help" instead of "facilitate."
- Fewer syllables per word: Prefer one-syllable words where possible.
- Active voice: "The team shipped the feature" not "The feature was shipped by the team."
Use the enhio text analysis tool to check your Flesch-Kincaid score instantly with sentence-by-sentence breakdown and improvement suggestions.