Readability Checker

Features

• Flesch Reading Ease and Flesch-Kincaid Grade Level
• Gunning Fog, SMOG and Coleman-Liau for comparison
• Long-sentence highlighting at a threshold you choose
• Passive voice and adverb detection
• Target comparison against four audience levels

How to use it

1. Paste your writing into the box.
2. Pick the audience you are writing for.
3. Read the score and check the highlighted sentences.
4. Work through the suggestions and re-check.

What these scores measure, and their limits

Flesch Reading Ease runs from 0 to 100, where higher is easier. It combines average sentence length and average syllables per word, that is genuinely all it looks at. Above 60 is considered plain English suitable for a general audience; below 30 is dense, academic prose. Flesch-Kincaid converts the same inputs into a US school grade level, which is why the two always move together.

Because the formulas only count sentence and word length, they can be gamed and they can be wrong. Chopping a clear sentence into fragments improves the score while making the writing worse. Technical terms your audience knows perfectly well, database, authentication: get penalised for syllable count, while short but obscure words sail through. A high score does not mean the writing is good; it means the sentences are short and the words are simple.

They remain useful as a signal rather than a verdict, and in some contexts they are mandatory: several US states require insurance policies to hit a specific Flesch score, and plain-language legislation often sets similar targets. The practical use is comparative, if a rewrite moves from grade 14 to grade 9, you have almost certainly made it more accessible. Use the highlighted sentences rather than the number as your editing guide.