Readability Score Calculator

Readability formulas estimate how hard a piece of text is to read using two basic signals: how long the sentences run, and how complex the words are. This calculator computes five widely published formulas at once from the same four counts, rather than making you pick one. Average Sentence Length (Total Words / Total Sentences) and Average Syllables per Word (Total Syllables / Total Words) feed the Flesch Reading Ease and Flesch-Kincaid Grade Level formulas directly, using their original published coefficients: Flesch Reading Ease runs roughly 0-100, where higher means easier to read, while Flesch-Kincaid Grade Level reports the approximate US school grade a reader needs to follow the text comfortably.

Gunning Fog Index uses sentence length together with the percentage of Complex Words (three or more syllables, excluding common suffixes like -ed, -es, and -ing) to estimate years of formal education needed -- a Gunning Fog score of 12 corresponds roughly to a graduating high school senior. Coleman-Liau Index and Automated Readability Index are both published formulas built on true letter and character counts, but since this calculator only collects syllable counts rather than letter counts, it estimates letters and characters from syllables using an average conversion factor (about 2.5 letters per syllable) rather than counting them directly -- treat these two scores as rougher estimates than the syllable-based Flesch and Fog scores, and expect them to drift further from a true letter-count calculation on text with unusually long or short words for their syllable count. Complex Words affects Gunning Fog Index only; it has no effect on any of the other four formulas, which rely purely on word, sentence, and syllable counts.