Flesch-Kincaid Readability Calculator
Paste any text and get the Flesch Reading Ease and Flesch-Kincaid Grade Level scores instantly — no button, no signup, no wait even on long documents.
How it works
- Paste your text into the box
- Both scores update live, with a plain-language difficulty label
- Sentence, word, and syllable counts are shown underneath for context
Frequently asked questions
How do I interpret the Flesch Reading Ease score?
It's a 0–100 scale where higher means easier to read. 90+ is very easy (5th grade level), while below 30 is very difficult (college graduate level).
Why does this work best on English text?
Syllable counting uses an English vowel-pattern heuristic, so accuracy drops for other languages — the Flesch-Kincaid formula itself was designed for English.
Does it slow down on longer documents?
No — the counting logic is lightweight pure JavaScript with a short debounce, so even long articles update without a noticeable delay.
What formulas does this calculator use?
Flesch Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Flesch-Kincaid Grade Level = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59. Rudolf Flesch published the Reading Ease formula in 1948, and J. Peter Kincaid's team adapted it into a U.S. school grade level in 1975 for the U.S. Navy.
What do the Flesch Reading Ease score ranges mean?
90–100: very easy (5th grade). 80–89: easy (6th grade). 70–79: fairly easy (7th grade). 60–69: standard (8th–9th grade). 50–59: fairly difficult (10th–12th grade). 30–49: difficult (college). 0–29: very difficult (college graduate).
What readability score should I aim for?
For writing aimed at the general public, such as web pages, product copy and instructions, a Reading Ease of 60 or higher (roughly 8th–9th grade) is a common target. Technical, legal and academic writing usually scores lower, which is fine when the audience expects it. Treat the score as a check on sentence and word length, not a verdict on quality.
How do I improve my readability score?
Both formulas only look at two things: average sentence length and average syllables per word. Split long sentences, and swap long words for shorter ones where the meaning stays the same (use for utilize, help for facilitate). Because syllables per word is multiplied by 84.6, cutting long words usually raises the Reading Ease score faster than shortening sentences.
Why does my score differ from other readability tools?
Tools count syllables and sentences differently. Syllable counts come from rules or dictionaries, and abbreviations, decimal numbers, headings without a period and bullet lists can all change where a sentence is judged to end. Differences of a few points between tools are normal, so compare drafts in the same tool.
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Update history
- 2026-10-16 Improved: added the Flesch and Flesch-Kincaid formulas, a score range table, target scores, tips for improving readability, and why scores differ between tools.
- 2026-09-09 Added: a color-coded gauge showing where your score falls on the very-difficult-to-very-easy scale, plus a downloadable for-fun certificate (PNG, with QR code) of your readability result.
- 2026-08-30 Added: a cover image — used as the card thumbnail, social share image, and blog title image.
- 2026-08-29 Launched: live Flesch Reading Ease + Flesch-Kincaid Grade Level scoring with debounced instant recalculation, no button, no signup.