Powers-Sumner-Kearl Readability Formula
Back in the day, in 1958, three guys created a powerful readability measure, the Power-Sumner-Kearl Readability Formula. They were R.D. Powers, B.E. Kearl, and W.A. Summer. This formula was published in a journal called A Recalculation of Four Adult Readability Formulas at the University of Wisconsin. Their readability formula, designed to improve reading by assessing readability level, was created mostly for the primary grades up to the 3rd-grade level. Their formula takes into consideration how many words are present, how many sentences there are, as well as the number of syllables.