Readability Checker
NewFlesch, Fog, Kincaid and SMOG on your text — plus the specific sentences making it hard to read.
Runs entirely in your browser
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How to use
- Paste the text you are about to publish.
- Read the reading ease first — it is the one score written for a general audience.
- Open the longest sentences and split the worst offenders.
- Watch the scores move as you edit; they update on every keystroke.
Features
- Five published formulas at once: Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, the Automated Readability Index and SMOG.
- Lists the longest sentences with their word counts, so there is something concrete to fix.
- Withholds SMOG until there are the thirty sentences it is defined on, rather than printing a number from too little text.
- Says when the sample is too small for the scores to be stable instead of reporting them with false confidence.
- Counts, sentences and averages work in any language written with spaces and full stops.
Frequently asked questions
- What is a good score?
- For writing aimed at a general audience, a Flesch Reading Ease of 60 to 70 is the usual target — roughly the reading level of a popular newspaper. Technical documentation for specialists routinely sits in the 30s and that is fine. The score is only a problem when it is far from the audience you are writing for.
- Does this work for Vietnamese?
- The counts do: words, sentences, average sentence length and the long-sentence list are all language-agnostic and useful. The grade levels do not. Every formula here was fitted on English prose against US school years, and syllable counting assumes English spelling, so read those numbers as English-only.
- Why did the score jump when I split one sentence?
- Because sentence length is half of every formula on this page. Splitting a forty-word sentence in two lowers the average for the whole text, which is exactly the effect the formulas were built to reward — long sentences are the most reliable predictor of difficulty that can be counted mechanically.
- Can a score be gamed?
- Easily, and that is the honest limit of it. Chopping every sentence into fragments and swapping long words for short ones will raise the reading ease without making anything clearer, because no formula reads meaning. Use the number as a prompt to reread, not as a target to optimise.
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