Analyze your text with multiple readability formulas including Flesch Reading Ease, Gunning Fog, and more.
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The Flesch Reading Ease formula, developed by Rudolf Flesch in 1948, calculates readability on a 0-100 scale where higher scores mean easier text. The formula is: 206.835 - 1.015(words/sentences) - 84.6(syllables/words). A score of 60-70 is considered standard for general audiences. Scores above 80 are easy enough for most readers, while scores below 30 indicate very difficult academic text. This formula is used by the US military, government agencies, and is built into Microsoft Word.
Created for the US Navy in 1975, the Flesch-Kincaid Grade Level formula outputs a US school grade level (1-12+) rather than a 0-100 score. The formula is: 0.39(words/sentences) + 11.8(syllables/words) - 15.59. A score of 8.0 means an 8th grader can understand the text. This is the most widely used grade-level formula and is the standard in Microsoft Word and many other word processors.
Developed by Robert Gunning in 1952, the Gunning Fog Index estimates years of formal education needed to understand text. The formula is: 0.4[(words/sentences) + 100(complex words/words)], where 'complex words' have 3+ syllables (excluding common suffixes like -es, -ed, -ing). A score of 12 means high school senior level, while 17+ indicates college graduate level. This formula is particularly effective for business and technical writing.
SMOG (Simple Measure of Gobbledygook), created by G. Harry McLaughlin in 1969, is considered the gold standard for healthcare and medical texts. The formula focuses exclusively on polysyllabic words (3+ syllables): 1.0430 × √(polysyllables × 30/sentences) + 3.1291. SMOG is more conservative than other formulas, often producing higher grade levels. It works best with 30+ sentences and is widely used in health literacy assessment.
Unlike most readability formulas, the Coleman-Liau Index (1975) uses character count instead of syllables. The formula is: 0.0588L - 0.296S - 15.8, where L = average letters per 100 words and S = average sentences per 100 words. This makes it faster to compute and more consistent across different analyzers. It returns a US grade level and is particularly useful for automated text processing systems.
Designed for the US military in 1967, ARI was created for easy calculation on typewriters. The formula is: 4.71(characters/words) + 0.5(words/sentences) - 21.43. Like Coleman-Liau, it uses character counts rather than syllables. The output is a US grade level, and unlike some formulas, ARI can return scores above 12 for very complex texts. It remains popular due to its computational simplicity.
Created by John O'Hayre at the US Bureau of Land Management to combat bureaucratic 'governmentese,' the Linsear Write formula classifies words as 'easy' (1-2 syllables) or 'hard' (3+ syllables). It calculates: (easy words + hard words × 3) / sentences, then applies an adjustment based on the raw score. This formula is particularly effective for technical documents, government publications, and instructional materials.
The Dale-Chall formula takes a unique approach by using a list of 3,000 words that 4th graders reliably understand. Any word not on this list is considered 'difficult.' The formula is: 0.1579(% difficult words × 100) + 0.0496(words/sentences), with an adjustment if difficult words exceed 5%. A score of 4.9 or below indicates text easily understood by 4th graders. This formula is particularly accurate for educational and children's content because it measures word familiarity rather than word length.
Flesch Reading Ease is a readability score from 0-100. Higher scores indicate easier text. 60-70 is considered standard, 70-80 is fairly easy, and 80-90 is easy enough for most audiences.
