Gunning Fog Index Calculator

The formula is 0.4 times the sum of two parts: the average number of words per sentence, and 100 times the fraction of words that are complex. The result is read as an approximate US grade level, where a lower number means easier text.

In the Gunning Fog method a complex word has three or more syllables. This tool decides syllable count with a vowel-group heuristic rather than a dictionary, so short common words stay simple while longer ones like organization or controversial register as complex.

Each word is lowercased, runs of consecutive vowels among a, e, i, o, u and y are counted as one syllable each, a trailing silent e is dropped, and every word is floored at one syllable. It is a fast estimate, not a phonetic dictionary.

Words are unbroken runs of letters and digits, so hyphens and punctuation act as separators. Sentences are counted from runs of period, exclamation mark or question mark, and any non-empty text counts as at least one sentence even without end punctuation.

With one sentence the words-per-sentence term equals the whole word count, which can be large, and a short sentence packed with long words also pushes the complex-word share up. Both effects stack, so a single dense sentence like 'The organization implemented a controversial new policy.' scores about 25.7. Longer, varied passages give a steadier reading.

The tool maps the index to a plain label: under 6 is Very Easy, 6 to 9 is Easy, 9 to 13 is Standard, 13 to 17 is Difficult, and 17 or above is Very Difficult. These bands are a rough guide to how demanding the text feels.

No. The complex-word tally relies on a syllable estimate, so unusual spellings, names and technical terms can be miscounted, which nudges the score. Treat the number as a close approximation and compare it against the other indices on the page.

For text meant to reach a wide audience, many editors target roughly 8 to 12, near the reading level of popular newspapers. Technical or academic writing naturally runs higher, so the right target depends on who will read it.

Yes. The score is computed entirely in your browser, so nothing you paste is uploaded, logged or stored anywhere.