Readability score checker
See how easy your writing is to read, with six standard formulas, an overall grade level and the long sentences and words that drag it down.
Runs in your browser. Your text is never uploaded or saved.
- Over 25 words
- 4+ syllables
Add some text to see which sentences and words make it harder to read.
0 words
Overall reading level
–
Paste or type some text and the scores appear here as you write.
Flesch reading ease
– out of 100
Grade-level formulas
- Flesch–Kincaid gradeSentence length and syllables
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- Gunning fog indexSentence length and complex words
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- SMOG indexWords of three or more syllables
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- Coleman–Liau indexLetters and sentences per 100 words
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- Automated readability indexCharacters per word, words per sentence
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How it’s calculated
Readability formulas count sentence length and word length, then scale the result to a school grade. Here are the exact formulas we use.
- Flesch reading ease
- 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words)A 0 to 100 scale where higher is easier. Most plain-English writing lands between 60 and 70; academic papers often score below 30.
- Flesch–Kincaid grade
- 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59The same two ingredients, rescaled to a US school grade. Grade 8 means most readers aged 13 to 14 can follow it.
- Gunning fog index
- 0.4 × [(words ÷ sentences) + 100 × (complex words ÷ words)]Complex words have three or more syllables, not counting proper nouns, hyphenated compounds, or syllables added by ‑es, ‑ed and ‑ing.
- SMOG index
- 1.043 × √(polysyllables × 30 ÷ sentences) + 3.1291Built on words of three or more syllables. It was designed for samples of 30 sentences, so it is less steady on short text.
- Coleman–Liau index
- 0.0588 × L − 0.296 × S − 15.8L is letters per 100 words and S is sentences per 100 words. It counts letters instead of syllables, so it never has to guess pronunciation.
- Automated readability index
- 4.71 × (characters ÷ words) + 0.5 × (words ÷ sentences) − 21.43Characters here are letters and digits. Like Coleman–Liau, it relies only on counts a computer can make exactly.
- Overall reading level
- The median of the five grade-level scores. Each formula has quirks; the middle value is steadier than any one of them.
- Syllables and highlights
- Syllables are estimated with spelling rules (vowel groups, silent endings and common exceptions), usually within one syllable of a dictionary. Sentences over 25 words are shaded; words of 4 or more syllables are underlined.
Readability questions
Anything else? The help center has more.
It depends on who you’re writing for. For websites, emails and most business writing, aim for a Flesch reading ease of 60 or more, or a grade level around 7 to 9. Technical and academic writing can go higher, but shorter sentences help every audience.
Each one weighs different things. Flesch–Kincaid and SMOG lean on syllables, Coleman–Liau and ARI on letters and characters, and Gunning fog on “complex” words. A text full of short but unusual words can score easy on one and hard on another, which is why we also show the median.
Start with the shaded sentences: split each one where it changes topic, or turn a list buried in the middle into its own sentence. Then look at the underlined words and swap any that have a shorter, common alternative, like “use” for “utilize”. Scores update as you edit.
These formulas were built and tested on English, and the syllable rules are English-specific. You’ll get numbers for other languages, but treat them as rough. Sentence and word length are still useful signals in any language.
No. Every score is calculated in your browser as you type. Nothing is uploaded, logged or stored, and the text is gone when you leave the page.
Next, check whether it reads as human
Paste the same text into the AI detector to see which sentences read as machine-written, with a score you can explain to someone else.