Flesch-Kincaid Readability Calculator — Grade Level & Reading Ease Score

How to use the Flesch-Kincaid readability calculator

1. Paste or type your text into the input box — an essay, an article, or any draft.
2. The calculator counts characters, words, sentences, and syllables by itself.
3. Read the two scores: Flesch Reading Ease (0–100) and Flesch-Kincaid Grade Level.
4. Edit your text and run the check again until the scores fit your target audience.

You can paste a whole document at once for the most reliable result. A single paragraph works for a quick check, but short samples give less stable scores. Most writers check, edit, and check again until the numbers land where they want.

A worked example, with the numbers

Here is exactly what the calculator does, using a sample passage of 120 words, 6 sentences, and 180 syllables.

First, it finds the two averages. Average words per sentence: 120 ÷ 6 = 20. Average syllables per word: 180 ÷ 120 = 1.5.

Then it applies the Flesch-Kincaid Grade formula: 0.39 × 20 + 11.8 × 1.5 − 15.59. That works out to 7.8 + 17.7 − 15.59 = 9.91, which rounds to grade 10.

Then the Flesch Reading Ease formula: 206.835 − 1.015 × 20 − 84.6 × 1.5. That works out to 206.835 − 20.3 − 126.9 = 59.635, which rounds to 60.

Grade 10 means the text is readable by a US 10th-grader — about 15 to 16 years old. A Reading Ease score of 60 is plain English that reads comfortably. If you needed grade 8 instead, you would shorten some sentences, swap long words for shorter ones, and check again.

When you need a readability score

• Checking an essay before submitting. Students can make sure their writing sits at the right grade level for the assignment.
• Writing blog posts for a wide audience. Bloggers and writers aim for a Reading Ease of 60 or higher to keep readers on the page.
• Levelling classroom worksheets. Teachers can match reading material to the age and ability of their class.
• Meeting plain-language standards. Content teams can check that public documents meet plain-language rules before publishing.

Limitations worth knowing

• Syllables are counted mechanically, so proper nouns and unusual words can skew the score.
• The formula penalises necessary technical vocabulary — expert writing scores harder than it actually reads for its own audience.
• Scores are unstable for texts under about 100 words, so very short samples can mislead.
• Both formulas were calibrated on English prose, so results for other languages are unreliable.

Flesch-Kincaid readability calculator – frequently asked questions

What is the difference between Flesch-Kincaid grade level and Flesch Reading Ease?

The grade level is the US school year a reader needs to understand the text — grade 8 means an eighth-grader can read it. Reading Ease is a 0–100 scale where a higher number means easier reading. The two scores measure the same thing from different angles.

What score should I aim for?

For general web writing, aim for grade 8–9 and a Reading Ease of 60–70. For a broad public audience — health information, for example — go lower, around grade 6–7, so most adults read it comfortably.

Why do two checkers disagree on the same text?

Different tools use different syllable-counting rules, and one extra or missing syllable per sentence moves the grade level. The gap is usually small — a grade or two — so treat the score as a guide, not a verdict.

Does it work for languages other than English?

No. Both formulas were calibrated on English prose, and syllable rules differ by language. Scores for other languages are unreliable.

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