Readability Calculator
Estimate English prose difficulty with the Automated Readability Index and transparent text counts.
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How to use Readability Calculator
Use an approximate reading-grade signal to review a draft. The Automated Readability Index uses characters per word and words per sentence; it does not test comprehension.
- Paste a sample of English prose.
- Calculate the index and review its underlying counts.
- Use audience testing and editorial judgment alongside the estimate.
Good to know
- ARI was designed for English prose. It is not a validated assessment for other languages, code, lists, or an individual reader.
- Unicode word/sentence boundaries can vary by browser, especially with abbreviations. Short samples are unstable.
- The estimate does not measure factual accuracy, accessibility compliance, comprehension, or writing quality.
Common questions
Why are there no syllable counts?
ARI uses letters/digits, words, and sentences rather than estimated syllables.
Can the raw score be negative?
Yes. The raw formula is reported without clamping; the grade label describes scores below one separately.
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