Readability Score Calculator
Flesch Reading Ease
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Flesch-Kincaid Grade Level
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US school grade
Words
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Sentences
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Syllables
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Characters
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Words / sentence
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Syllables / word
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How to Use
Paste or type your English text into the input area. The Flesch Reading Ease score (0-100, higher is easier), Flesch-Kincaid Grade Level (US school grade), and underlying counts update in real time as you edit. Use the scores to judge whether your writing matches the reading level of your intended audience.
What Are Readability Scores
Readability scores estimate how difficult a piece of text is to read, based on measurable properties: average sentence length and average word complexity (measured in syllables). They were originally developed in the 1940s for US Navy training materials and are now widely used in education, publishing, content marketing, and UX writing. Two colored-pencil formulas are shown here — they are not perfect, but they are fast, well-understood, and a useful sanity check.
The Two Formulas
Flesch Reading Ease = 206.835 − 1.015 × (words / sentences) − 84.6 × (syllables / words). It scores from about 0 (very hard) to about 100 (very easy). 60-70 is plain English and what most general-audience writing aims for. Flesch-Kincaid Grade Level = 0.39 × (words / sentences) + 11.8 × (syllables / words) − 15.59. It returns a number corresponding to a US school grade — so a score of 8 means the text should be understandable by an 8th grader (age 13-14).
Common Use Cases
- Writers, journalists, and bloggers checking that their copy is accessible to a general audience.
- Marketing and content teams aligning copy with brand voice and target reading level.
- UX writers shortening help text and error messages so users at all literacy levels can understand.
- Teachers matching reading materials to student grade levels.
- Technical writers keeping documentation approachable, not just technically accurate.
- Non-native English writers checking that their writing is not unnecessarily complex.
Tips
- Most general-audience writing targets Flesch Reading Ease 60-70 (plain English).
- Shortening sentences lowers your grade level faster than changing vocabulary.
- Multi-syllable words like "utilize" inflate the score — prefer simpler synonyms like "use".
- The formulas were designed for English — results for other languages are not meaningful.
- Very short inputs (a few words) produce unstable scores; use at least a paragraph for a meaningful reading.
Privacy
All readability calculations happen in your browser. Your text is never sent to any server or stored anywhere.
FAQ
What is the difference between Flesch Reading Ease and Flesch-Kincaid Grade Level?
Flesch Reading Ease is a 0-100 score where higher means easier to read. Flesch-Kincaid Grade Level instead returns the US school grade needed to understand the text. Use the first for an intuitive sense of readability and the second when you need to target a specific grade.
Is my text sent to a server?
No. Every calculation, including syllable counting, runs purely in your browser with JavaScript. You can paste unpublished drafts or internal documents — nothing is uploaded, stored, or logged.
Can I score Japanese or other non-English text?
These two formulas are built around English syllable structure, so they produce no meaningful result for Japanese or other languages. Enter English text to get an accurate readability reading.
How much text do I need for an accurate score?
With only a few words, the words-per-sentence and syllable ratios swing wildly and the score becomes unstable. Enter at least one paragraph — ideally several — for a reliable result.
How can I lower the grade level of my writing?
The most effective change is shortening your sentences, which improves the score faster than swapping vocabulary. Replacing multi-syllable words like "utilize" with simpler ones like "use" helps further.