Readability Checker
Flesch Reading Ease, Flesch-Kincaid grade and Gunning Fog, with the inputs shown.
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How to use Readability Checker
Paste at least a paragraph
These formulas are averages. Under roughly 100 words the numbers swing wildly on a single long sentence.
Choose your audience
This sets the threshold the score is judged against. The score itself never changes.
Fix the biggest lever first
Average sentence length usually moves the score more than word choice. Split the long sentences before hunting for shorter synonyms.
Why use this readability checker
Runs on your device
Your input is handled entirely in this browser tab. Nothing is uploaded, so there is nothing for us to store, log or leak.
No sign-up, no quota
No account, no daily limit, no watermark and no email wall. Use it once or two hundred times a day.
Built to be linked
Options are stored in the URL, so a configured tool is a link you can send to a colleague or bookmark.
Technical notes
Most readability tools return one number and nothing else. This one shows the two inputs every formula is built on — average sentence length and average syllables per word — plus the count of three-syllable words. Those three numbers tell you what to change; the score on its own only tells you that something is wrong.
What each score band means in practice
| Reading Ease | Grade level | Comparable to |
|---|---|---|
| 90–100 | 5th grade | Children’s writing |
| 70–80 | 7th grade | Popular fiction |
| 60–70 | 8th–9th grade | Plain English; most news writing |
| 30–50 | University | Trade press, technical documentation |
| 0–30 | Postgraduate | Academic papers, legal contracts |
Supported
- Flesch Reading Ease (Flesch, 1948)
- Flesch-Kincaid Grade Level (Kincaid et al., 1975)
- Gunning Fog Index (Gunning, 1952)
- The underlying sentence-length and syllable inputs, not just the scores
Limits and trade-offs
- English only. Syllable heuristics do not transfer to other languages.
- Syllable counting is heuristic, so expect ±2 points against a hand count.
- Sentence detection is punctuation-based: "Dr. Smith" reads as two sentences and pulls the score up.
- These formulas measure surface complexity, not clarity. A short, badly organised paragraph scores well.
Last verified August 2026 · benchmarks re-run each quarter.
Frequently asked questions
What is a good Flesch Reading Ease score?
Sixty to seventy is plain English, understandable by most adults, and the range most newspapers and general-audience writing land in. Above eighty is very easy. Below thirty is dense enough that a specialist reader will still have to slow down.
What is the difference between Reading Ease and the Flesch-Kincaid grade?
They use the same two inputs — average sentence length and average syllables per word — but scale them differently. Reading Ease is a 0-100 score where higher is easier. Flesch-Kincaid converts the same data into a US school grade level, where lower is easier.
How are syllables counted?
By a vowel-group heuristic with adjustments for silent "e" and common suffixes. It is accurate to about one syllable per word on ordinary prose. Every implementation of these formulas uses a heuristic, which is why scores differ slightly between tools.
How much text do I need for a reliable score?
At least 100 words, and ideally 200. These are averages across sentences, so on a short sample one 40-word sentence can move the score by ten points on its own.
Do these formulas work for languages other than English?
No. Flesch and Gunning Fog were both calibrated on English and depend on English syllable patterns. A score for German, Bangla or Spanish text will be produced but it is not meaningful — use a formula built for that language.
Does a higher readability score help SEO?
Not directly. There is no readability signal in any published ranking system. It helps indirectly: text people can read is text people finish, and completion is what search engines can actually observe.