What is a readability score?
A readability score estimates how easy a piece of text is to read. It is based on things that are easy to measure: how long your sentences are and how long your words are (in syllables or letters). Long sentences and long words make readers work harder. Readers who work harder skim, bounce or miss your message.
Clear writing isn’t about “dumbing down”. Even experts prefer plain language. In one well-known study, lawyers preferred plain-English versions of legal text over traditional legalese.
The six formulas explained
| Score | What it measures | Good target |
|---|---|---|
| Flesch Reading Ease | Sentence length + syllables per word, from 0 to 100 (higher is easier) | 60+ |
| Flesch-Kincaid Grade | The same inputs as a US school grade (used by the US Navy and many governments) | 7–9 |
| Gunning Fog | Sentence length + share of “complex” (3+ syllable) words | Under 12 |
| SMOG | Polysyllabic words. Widely used for health information | Under 10 |
| Coleman-Liau | Letters per word instead of syllables | Under 10 |
| Automated Readability (ARI) | Characters per word + words per sentence | Under 10 |
No single formula is perfect, so we show all six and an average grade. If they all point the same way, you can trust the result.
7 quick ways to improve readability
- Split long sentences. Anything highlighted in red (30+ words) can almost always become two sentences.
- Prefer short, common words: “use” instead of “utilise”, “help” instead of “facilitate”, “buy” instead of “purchase”.
- Use the active voice. “The team wrote the report” is clearer than “The report was written by the team”.
- Cut weak adverbs. “Ran quickly” becomes “sprinted”. “Very important” becomes “critical”.
- One idea per paragraph, and keep paragraphs to 2–4 lines on mobile.
- Use subheadings and bullet lists so skimmers can find what they need.
- Talk to the reader with “you” and “we”. It feels human and naturally shortens sentences.
Does readability affect SEO? Google doesn’t use a Flesch score as a ranking factor. But readable pages keep people reading, earn more links and shares, and answer questions clearly. Those things do help your rankings and conversions.
How the highlights work
Sentences over 20 words are highlighted yellow, and those over 30 words red. Passive voice is found by looking for a form of “to be” followed by a past participle (was written, is being built). Adverbs are words ending in “-ly”, excluding common non-adverbs like family, early or reply. Treat highlights as suggestions, not rules. Sometimes a long sentence or a passive phrase is exactly right.