Readability Checker
Note: These formulas measure sentence length and word length, and nothing else. Well-formed nonsense scores as well as a clear argument — so treat a good number as the absence of one problem, not as evidence the writing works.
Knowing that is what makes the score useful, because it tells you exactly which lever to pull. A poor score means sentences are long, or words are polysyllabic, or both. Splitting one long sentence at its conjunction and replacing one Latinate word with its plain equivalent moves the number more than any amount of rewriting around the edges. That is why the sentences dragging the score down are listed individually here, rather than only reporting an average — the average is rarely the problem, and two or three sentences usually account for most of it.
Four formulas are shown because they disagree in informative ways. Flesch Reading Ease runs 0 to 100 with higher being easier. Flesch–Kincaid converts the same inputs to a US school grade. Gunning Fog weights words of three or more syllables heavily, so it punishes technical vocabulary hardest. SMOG was designed for health materials and is the most conservative. When Fog is far above the others, the problem is vocabulary rather than sentence length.
The usual target for general web writing is grade 8 to 10 — not because readers cannot manage more, but because most are skimming on a phone.
Frequently Asked Questions
What score should I aim for?
Grade 8 to 10, or a Flesch Reading Ease of 60 to 70, for general web writing. Not because the audience is incapable of more, but because most of them are skimming on a phone between other tasks. Technical documentation for a specialist audience can sit higher without any problem.
Is readability a ranking factor?
Not directly — search engines have said as much repeatedly. It affects the things that are measured: whether people stay, read and act. A page nobody finishes performs badly regardless of what the formula said about it.
Why do the four scores disagree?
Because they weight the same inputs differently. Gunning Fog penalises words of three or more syllables heavily, so it rises fastest on technical vocabulary. SMOG is deliberately conservative. When Fog sits well above the others, your problem is word choice rather than sentence length.
How is syllable counting done?
By counting vowel groups with adjustments for silent endings and common exceptions. It is an approximation — English spelling makes an exact count impossible without a dictionary — and it is accurate to within a few percent over any reasonable amount of text, which is enough for a score that is itself a rough guide.
Can I paste HTML?
Yes. Tags are stripped before analysis, so pasting a rendered article or a block of markup both work. Code blocks will skew the result, since a variable name reads as a very long word — remove them for a fair score.
