What the scores measure
Readability formulas look at two things: how long your sentences are and how long your words are (measured in syllables). They cannot judge meaning or grammar, but they are a quick, objective way to see whether your writing is likely to feel dense or choppy to a reader.
- Flesch Reading Ease (0–100): higher is easier. 60–70 is plain English; 30–50 is typical of academic writing.
- Flesch–Kincaid Grade: the US school grade needed to understand the text.
- Gunning Fog index: years of formal education needed, based on sentence length and words with three or more syllables.
Why it matters for IELTS
Coherence and Cohesion is a quarter of your Writing score, and it depends partly on how easily the examiner can follow your ideas. Grammatical Range and Accuracy rewards a mix of simple and complex sentences that are written accurately. Very long sentences make both harder: they hide errors and blur the logic of your argument. Very short sentences throughout suggest a limited grammatical range.
Worked example
“Many people believe that the government should invest more money in public transport because it reduces traffic and pollution and it also helps people who cannot afford cars and therefore it is better for society.” This single 38-word sentence would be highlighted in red. Splitting it into two sentences — and replacing “and therefore” with a clear linking phrase such as “As a result” — keeps the same ideas while making the argument much easier to follow.
How to use the results
- Aim for an average of roughly 15–22 words per sentence, with some variety.
- Split red sentences, and check amber ones for missing commas or repeated “and”.
- Pair this with the vocabulary level checker to make sure clarity doesn’t come at the cost of lexical range.