Automated Readability Index (ARI)
Calculate the Automated Readability Index for any text. Uses characters per word and words per sentence for grade level.
About This Free Online Automated Readability Index (ARI)
Our free online Automated Readability Index (ARI) calculator measures text readability using characters per word and words per sentence. Unlike syllable-based formulas, ARI uses character counts which are more reliable for automated analysis. The output is a US school grade level. ARI is widely used in educational software, content management systems, and text analysis tools. It tends to correlate well with other readability formulas while being simpler to compute.
Features of Our Automated Readability Index (ARI)
- Calculate ARI grade level instantly
- Character-based — no syllable counting
- Grade level output with interpretation
- Detailed word, character, and sentence stats
- Real-time analysis as you type
- 100% private — browser-only processing
How to Use the Automated Readability Index (ARI)
The Automated Readability Index (ARI) works right in your browser — no signup, no installation. Follow these steps:
- Paste your text into the input area.
- View your ARI grade level instantly.
- Review statistics including characters per word and words per sentence.
- Adjust your writing to match your target audience reading level.
Frequently Asked Questions About Automated Readability Index (ARI)
How is the ARI calculated?
The formula is: 4.71 × (characters / words) + 0.5 × (words / sentences) - 21.43. The result is a US grade level.
How does ARI compare to Flesch-Kincaid?
ARI and Flesch-Kincaid generally produce similar grade levels, but ARI uses character counts instead of syllable counts. This makes ARI more reliable for computer analysis since character counting is exact.
What grade level should I aim for?
For general audiences, aim for grade 7-8. For broad accessibility, grade 6 or below. For technical content, grade 10-12 may be appropriate.
Why Choose the Automated Readability Index (ARI)?
Text Toolbox provides free, private, and instant online tools. Unlike sites that require accounts or send your data to servers, the Automated Readability Index (ARI) processes everything in your browser — your content never leaves your device. It is fast, lightweight, and works on any modern browser.