Score readability from polysyllable words and sentence count.
SMOG counts words of three or more syllables and related them to sentence count, leaning heavily on difficult vocabulary. It is often the recommended index for health and safety text because of its scoring at higher grade levels. SMOG tends to grade a little more strictly than other readability measures, making it a cautious choice wherever clarity is a legal or safety concern.
SMOG Index
SMOG = 1.043 x sqrt(polysyllables x 30/sentences) + 3.1291
SMOG = 1.043 x sqrt(polysyllables x 30/sentences) + 3.1291 SMOG counts words of three or more syllables and related them to sentence count, leaning heavily on difficult vocabulary. It is often the recommended index for health and safety text because of its scoring at higher grade levels.
SMOG tends to grade a little more strictly than other readability measures, making it a cautious choice wherever clarity is a legal or safety concern.
This calculator takes 2 inputs: Sentences, Polysyllable words. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.