Readability Score Calculator
Readability formulas measure two things and only two: how long your sentences are, and how many syllables your words have. That is genuinely useful as a rough signal, and it is also why a passage of pure nonsense can score beautifully. This gives you all four common measures at once, and is direct about what they cannot tell you.
What this generator does
Counts words, sentences and syllables in your text, then reports Flesch Reading Ease, the Flesch-Kincaid grade, the Gunning Fog index and SMOG, alongside the two averages that drive all four: words per sentence and syllables per word.
How to use this tool
- Paste your text into the box.
- Read the four measures — they will not agree exactly, and that is expected.
- Look at words per sentence first, since it drives every one of the formulas.
- Treat a poor score as a prompt to reread, not as an instruction to chop sentences up.
Understanding the controls
- Your text
- At least 40 characters, since these measures are meaningless on a fragment, and up to 4,000. It is analysed on your own device and never sent anywhere.
Common use cases
- Checking whether a public-facing document is pitched at the right level
- Comparing drafts to see whether a rewrite actually simplified anything
- Teaching how the formulas work and what they miss
- Meeting a plain-language target for a form or a policy
- Sanity-checking writing aimed at a wide audience
How this generator works
Sentences are split on full stops, question marks and exclamation marks; syllables are counted by grouping runs of vowels, with common silent endings removed first. That syllable count is a heuristic rather than a dictionary lookup, so it will be wrong on some words — it is the same approximation every implementation of these formulas makes, and it is worth knowing rather than hiding.
Randomness and fairness
Nothing here is random. Every figure follows deterministically from the text you enter, so the same passage always scores identically.
For how randomness is produced across the whole site, see how Generate Random works.
Limitations and good to know
- The formulas count syllables and sentence lengths. None of them can judge whether writing is clear, accurate, well organised or worth reading.
- A text can be made to score well by chopping long sentences into short ones without improving it at all.
- Syllable counting is a heuristic and will be wrong on some words, particularly names and unusual spellings.
- The grade levels refer to United States school years, which travel poorly to other education systems.
- Tuned for English prose; poetry, lists, code and other languages give meaningless results.
Privacy and your data
Your text is analysed entirely in your browser and never transmitted. Analytics records only that the tool ran and roughly how much text was involved, never any of the words.
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