In short: A readability checker estimates how easy English text is to read using formulas such as Flesch Reading Ease (0–100, higher is easier) and Flesch–Kincaid Grade Level (approximate US school grade).
About Readability Checker
Plain-language guidelines from governments and accessibility standards recommend writing public content at around a US grade 8 level. Readability formulas give a quick, objective estimate based on sentence length and word length — long sentences full of polysyllabic words score as harder.
This checker calculates five well-known scores: Flesch Reading Ease (Rudolf Flesch, 1948), Flesch–Kincaid Grade Level (developed for the US Navy in 1975), Gunning Fog, SMOG and Coleman–Liau. Syllables are counted with a rule-based English estimator, which is accurate for the large majority of words. The longest sentences are listed so you know what to shorten first.
How to use Readability Checker
- Paste at least a few sentences of English prose.
- Read the scores — they update as you type.
- Shorten the longest sentences and replace long words to make the text easier.
Examples
Flesch Reading Ease 60–70 is plain English suitable for most adults; 30–50 is college level; below 30 is very difficult (academic or legal).
Splitting one 40-word sentence into two 20-word sentences can raise Flesch Reading Ease by 10 points or more.
Frequently asked questions
What is a good readability score?
For general web content, aim for Flesch Reading Ease above 60 and a grade level of 8 or lower.
Why do the formulas disagree?
Each formula weights sentence length, syllables and characters differently. Look at the overall trend rather than one number.
Does it work for other languages?
No. The formulas and syllable counter are calibrated for English.
Is my text uploaded?
No. Analysis happens in your browser. You can check this yourself: open your browser’s developer tools, switch to the Network tab and use the tool — no request carries your input.
Updated November 2026 · Free, no signup · How we build and test tools