Paste any text to see its Flesch–Kincaid Grade Level and Flesch Reading Ease score — two classic readability measures used by editors, teachers, and content teams to keep writing at the right level for its audience. Scores update instantly as you type.
How it works
The tool counts words, sentences, and syllables, then derives two averages: words per sentence and syllables per word. Syllables are estimated by counting vowel groups in each word. It then applies the two standard Flesch formulas:
- Flesch–Kincaid Grade Level = 0.39 × (words/sentence) + 11.8 × (syllables/word) − 15.59. The result is a US school grade, so 8.0 means an average 8th-grader can follow the text.
- Flesch Reading Ease = 206.835 − 1.015 × (words/sentence) − 84.6 × (syllables/word). Higher is easier; the scale runs 0–100.
Longer sentences and longer (more syllabic) words both raise the grade and lower the ease score.
The two scores explained
Grade level and reading ease are derived from the same two averages but weighted differently, so they are not simple inverses of each other. A text with very short sentences but many two-syllable technical words could have a deceptively low grade yet genuinely hard vocabulary. Checking both scores together gives a fuller picture.
| Reading Ease | Grade (approx.) | Typical audience |
|---|---|---|
| 90–100 | Below 5th | Very easy — children’s books, simple instructions |
| 70–80 | 6th–7th | Easy — consumer product copy, news summaries |
| 60–70 | 8th–9th | Plain English — web copy, general media |
| 50–60 | 10th–12th | Fairly difficult — professional documents |
| 30–50 | College | Difficult — academic journals, legal texts |
| 0–30 | Graduate | Very hard — specialist technical literature |
What to aim for
The right grade depends on your audience and purpose:
- General consumer web copy: aim for grade 6–8, ease 60–70.
- Email marketing: grade 5–7, ease 65–75 performs well in most studies.
- Healthcare patient materials: many clinical guidelines recommend grade 6 or below, since health literacy is often lower than formal education suggests.
- Technical documentation for engineers: grade 10–14 is expected and appropriate.
- Legal contracts: grade 15+ is common but often criticised; plain-language legal reform advocates target grade 8–10 for consumer-facing documents.
Practical editing strategies
The grade level is sensitive to two levers: sentence length and syllables per word. The fastest gains come from:
- Breaking long sentences. A 40-word sentence containing three clauses is almost always clearer as two or three separate sentences.
- Replacing multisyllabic words with shorter synonyms. “Utilise” → “use”, “demonstrate” → “show”, “approximately” → “about”. Each swap cuts syllables and lowers the grade slightly.
- Removing throat-clearing phrases. Opening clauses like “It is worth noting that…” or “It should be emphasised that…” add length and complexity without adding meaning.
Paste a revised paragraph and watch the score move in real time.
Limitations to keep in mind
The syllable count is a vowel-group heuristic — fast and accurate enough for prose, but it can miscount unusual proper nouns, contractions, or words with silent vowels. The formulas were developed primarily on English prose and do not transfer to highly technical nomenclature, code snippets, or languages other than English. All scoring is local; nothing is uploaded.