Readability Scorer

Flesch, Flesch-Kincaid, Gunning Fog and SMOG scores for your text, in one paste.

Paste your text and get four standard readability scores at once: Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog Index and SMOG Grade. All four were built for English, and all four count the same two things in different ways: how long your sentences are, and how long your words are. Syllables are counted by rule (vowel groups, silent final e, and the consonant plus le ending), so a score can differ by a point from a dictionary-based counter on unusual words. The tool also lists your longest sentences, because one long sentence is usually the fastest fix.

Your text

Honest limits. These formulas were built for English school and training texts. They do not work for other languages, they do not judge whether your writing is good, and they cannot see organisation, tone or truth. A short text gives jumpy scores: SMOG in particular was designed for 30 sentences, so on a short passage it is a rough guide only. Complex words here mean words of 3 or more syllables, counted for every word, including names. The classic Fog definition leaves out proper nouns and a few common suffixes; leaving them in is the simpler, repeatable choice, and it pushes the Fog score slightly higher on texts full of names.

The four formulas, in plain words

Flesch Reading Ease (Rudolf Flesch, 1948) runs from 0 to 100, and higher is easier: 206.835 minus 1.015 times average sentence length, minus 84.6 times average syllables per word. A score of 60 to 70 is plain English. Flesch-Kincaid Grade Level (Kincaid and colleagues, 1975, for the US Navy) turns the same two counts into a US school grade: 0.39 times average sentence length, plus 11.8 times average syllables per word, minus 15.59. Gunning Fog (Robert Gunning, 1952) adds the share of complex words: 0.4 times (average sentence length plus 100 times complex words divided by all words). SMOG (Harry McLaughlin, 1969) counts complex words across 30 sentences: 1.043 times the square root of (complex words times 30 divided by sentences), plus 3.1291.

Use the four together, not one alone. If Reading Ease says easy but Fog says hard, your sentences are short but your words are long. If the grade level says grade 12 but your readers are general readers, shorten sentences first: cutting a 30-word sentence in two moves every score more than swapping one long word does. Aim for grade 8 or below for general web readers, and grade 6 or below for public information that everyone must understand.

What counts as a sentence or a word

Sentences end at a full stop, exclamation mark or question mark. Words are runs of letters and digits, so hyphenated words count as one word and numbers count as words. A fragment with no letters is not counted as a sentence, so a list of bare numbers will not inflate the sentence count.

What score should you aim for

General web writing: Reading Ease 60 or above, grade 8 or below. News writing: grade 8 to 10. Academic and legal writing will score higher grades by nature, and forcing it down can hurt precision. The score is a check on clarity, not a target to game by chopping every sentence to five words.

Frequently Asked Questions

A score from 0 to 100, higher is easier, published by Rudolf Flesch in 1948: 206.835 minus 1.015 times average sentence length, minus 84.6 times average syllables per word. A score of 60 to 70 is plain English that most readers handle easily.

The same two counts turned into a US school grade, recalculated by Kincaid and colleagues in 1975 for the US Navy: 0.39 times average sentence length, plus 11.8 times average syllables per word, minus 15.59. Grade 8 means an eighth-grade reader can follow it.

Robert Gunning's 1952 index: 0.4 times (average sentence length plus 100 times complex words divided by all words), where complex means 3 or more syllables. It estimates years of formal education needed to read the text on first reading.

Harry McLaughlin's 1969 index: 1.043 times the square root of (complex words times 30 divided by sentences), plus 3.1291. It was designed to be counted by hand across 30 sentences, so on shorter texts it is a rough guide only.

Because they weight the same counts differently. Fog and SMOG care only about long words, while Flesch cares about all syllables. Short sentences with long words score easy on one and hard on another. Read them together: the pattern across the four tells you whether sentences or words are the problem.

No. These formulas were built and tested on English. Syllable rules, sentence length norms and grade levels do not transfer. Scores on non-English text are meaningless, and the tool says so rather than printing a confident grade.

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