Readability Checker
Flesch, Gunning Fog, SMOG and three more, with sentence rhythm.
Needs a bit more text
At least ten words and one complete sentence, so the formulas have something to work with.
These are formulas, not judgements. Every one of them measures word and sentence length as a proxy for difficulty. None of them can tell whether the writing is clear, accurate or well argued — a short sentence can still be confusing. Use them to spot passages worth rereading, not as a target to optimise.
Private by design. This tool runs entirely in your browser. Your input is processed on your own device and is not uploaded by DO101.
About the Readability Checker
Six published readability formulas calculated on your text, plus the things they miss: sentence-length variance, a bar chart of every sentence, and your longest sentences pulled out for a second look. Useful for pitching an essay at the right level or getting web copy under a target grade.
How to use it
- 1Paste at least a paragraph — the formulas need about 100 words to settle.
- 2Read the Flesch Reading Ease score and what it means for your audience.
- 3Compare the five grade-level formulas; they disagree by design.
- 4Check the sentence rhythm chart for monotony and overlong sentences.
What you get
- Flesch Reading Ease, with a plain description of the audience
- Five grade-level formulas: Flesch–Kincaid, Gunning Fog, SMOG, Coleman–Liau, ARI
- Median grade, which is a fairer summary than any single formula
- Sentence-length variance — the rhythm no formula reports
- A bar per sentence, colour-coded by length
- Your longest sentences listed for rewriting
Frequently asked questions
Which score should I use?
Flesch Reading Ease for a quick sense of difficulty, Flesch–Kincaid if you have been given a grade-level target. If they disagree sharply, look at why: Coleman–Liau and ARI count characters, so long names push them up, while Fog and SMOG count long words.
What is a good score?
It depends entirely on the audience. General web writing usually aims for Reading Ease 60–70 (about grade 8–9). Academic writing sits far lower and that is appropriate — a philosophy essay scoring 70 would probably be underexplaining.
Are the syllable counts accurate?
English spelling is irregular, so no rule set is perfect. This one handles the common irregular words from a lookup table and applies vowel-group rules with silent-E and suffix corrections, landing within a syllable essentially always — comfortably inside what the formulas need.
Can I optimise my writing for these scores?
You can, but be careful what it does to your prose. All six formulas measure word and sentence length as a proxy for difficulty. Chopping every sentence in half will improve the number and can make the writing worse.
Keep going
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