Readability Checker
Paste your writing to check sentence length, the kanji-to-kana ratio, repeated sentence endings, runs of conjunctions and comma use. You get an overall score, a metrics table and highlighted problem sentences. Tuned for Japanese, with basic support for English. To measure quantity rather than quality, use the Character Counter or the Reading Time Calculator; to compare drafts, try the Text Diff. Your text is processed in the browser and never sent to a server.
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Overall score
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Metrics
Highlighted text
Flagged sentences
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Notes
- This is a lightweight check based on character types and regular expressions. It does not use morphological analysis, so ending and conjunction detection can be wrong.
- Sentences are split at Japanese and Western sentence-end marks and at line breaks. Marks inside quotation brackets also split a sentence, so dialogue-heavy text may show more sentences than it really has.
- For sentences without Japanese characters, length is estimated as three times the word count, so English is judged against the same limit.
- The kanji ratio is kanji divided by kanji, hiragana and katakana combined. It is not evaluated when there are fewer than 30 Japanese characters. The right value depends on genre, so treat it as a guideline.
- The overall score is a rough figure derived from the share of flagged sentences. It is a reference, not a verdict on the quality of your writing.
Related tools
- Character Counter — count characters, words and lines
- Reading Time Calculator — estimate how long a text takes to read
- Text Diff — compare drafts before and after editing
FAQ
How long should a sentence be?
Japanese sentences are generally easy to read up to roughly 40 to 60 characters. The default limit here is 60, and you can change it with the max sentence length field. Technical and legal writing often runs longer, so adjust it to fit your purpose.
What is a good kanji ratio?
The ratio is kanji divided by kanji, hiragana and katakana combined, and about 15 to 40% is a common guideline. Too high feels stiff and dense; too low makes word boundaries hard to see. Text with fewer than 30 Japanese characters is not evaluated.
Why are repeated sentence endings flagged?
Three or more sentences in a row ending the same way (for example three in a row ending in です) sound monotonous. The tool groups endings such as です, ます, だ and ない and flags the whole run.
Does it work for English text?
Partly. It is tuned for Japanese. For sentences without Japanese characters, length is estimated as three times the word count, and ending repetition and kanji ratio are skipped. Conjunction runs and comma counts are still checked.
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