無料 可読性チェッカー

GPTINF's Readability Checker analyzes your text using standard, well-established formulas — Flesch Reading Ease and Flesch-Kincaid Grade Level — along with average sentence length, to estimate how easy your writing is to follow and what grade level it corresponds to. Paste or upload your content and the tool returns a full breakdown: an overall reading-ease score, a grade-level estimate, word count, and estimated reading time, alongside sentence-by-sentence highlights that flag very hard and hard-to-read sentences directly in your text.

Readability is not about dumbing down your writing; it is about matching your sentence complexity to your actual audience and purpose. A technical whitepaper for specialists can reasonably score at a higher grade level than a blog post aimed at general readers, so use the score alongside context rather than as an absolute target. The highlighted sentences make it easy to find exactly where a paragraph gets dense — often because a sentence has grown too long, stacked too many clauses together, or lost its clear subject-verb structure — so you know precisely what to simplify or split without cutting content your readers actually need.

Readability works well paired with GPTINF's other tools: run the Grammar Checker first to fix mechanical errors, then check readability to catch structural and pacing issues a grammar check alone will not find, and use the Paraphrasing Tool to rework specific hard sentences into clearer language. Writers preparing content for students, customers, or a general audience often check readability right before publishing, since it is one of the fastest ways to catch passages that will lose a reader's attention.