Readability checker (Flesch, Fog, SMOG)

How to use

1. Paste English text into the box (100 words or more works best).
2. Choose a target reading level. Grade 8 is a common goal for a general audience.
3. Read the overall grade, the five scores and the statistics, then use "Sentence by sentence" to find long or hard sentences to rewrite.

Notes and limits

• Only English text is analyzed. Text that is mostly Korean, Japanese or another non-Latin script gets no scores, whatever the page language.
• Syllables are estimated from spelling rules, not a dictionary. Common words are counted almost always correctly, but names, loanwords and rare words can be off by one syllable, so scores can differ slightly from other tools.
• Texts under 100 words give less reliable scores, and SMOG was designed for samples of 30 sentences or more. The page tells you when either applies.
• Readability formulas only measure word and sentence length. They cannot judge clarity, logical order or what your readers already know.

How it works

Flesch Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Flesch–Kincaid Grade = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59.

Gunning Fog = 0.4 × (words per sentence + 100 × share of complex words). Complex words have three or more syllables, excluding hyphenated words, capitalized words in mid-sentence (treated as proper nouns) and words that reach three syllables only through -es, -ed or -ing.

Coleman–Liau = 0.0588 × L − 0.296 × S − 15.8, where L is letters per 100 words and S is sentences per 100 words. SMOG = 1.043 × √(words of 3+ syllables × 30 ÷ sentences) + 3.1291.

Sentences end at . ! or ? followed by a space, or at a blank line. Abbreviations such as Mr., Dr. and e.g., initials, decimals and a following lowercase word do not end a sentence. A single line break counts as a space.

Syllables are estimated by counting vowel groups (a e i o u y), dropping a silent final e and silent -es/-ed endings, and correcting vowel pairs that are usually two syllables (such as ia and ua). On the list of about 200 common words used to tune the rules, one word differs from the dictionary count, by one syllable.