📖 Readability Score Calculator

Flesch Reading Ease

206.835 − 1.015×(words/sentences) − 84.6×(syllables/words). Scores 0–100; higher = easier. Widely used in US government and publishing.

Score 60–70 targets general adult audience.

Flesch-Kincaid Grade

0.39×(words/sentences) + 11.8×(syllables/words) − 15.59. Maps directly to US school grade levels. Adopted by US DoD for document standards.

Grade 8 = 8th grade (13–14 year olds).

Gunning Fog Index

0.4×[(words/sentences) + 100×(complex words/words)]. Complex = 3+ syllable words. Index 12 = high school graduate required to comprehend.

Target 8 or below for mass-market content.

SMOG Index

√(polysyllables × 30/sentences) + 3. Developed by G. Harry McLaughlin (1969). Highly accurate for health literacy materials. Requires 30+ sentences.

Coleman-Liau Index

Uses characters per word instead of syllables: 0.0588×L − 0.296×S − 15.8 where L = avg letters/100 words, S = avg sentences/100 words.

Automated Readability

4.71×(chars/words) + 0.5×(words/sentences) − 21.43. ARI was designed for real-time monitoring of US Air Force technical documents in the 1960s.

Dale-Chall Formula

Uses a 3,000-word "familiar words" list. Words outside this list are "difficult." Adjusts for difficult word percentage × avg sentence length. Best for elementary reading assessment.