The Powers-Sumner-Kearl formula estimates the U.S. grade level needed to read elementary-grade text. Pairs naturally with Spache and Dale-Chall.
Use Powers-Sumner-Kearl for elementary text. It pairs naturally with Spache for K-4 readers and Dale-Chall for grades 4-8. Originally a simplified variant of Flesch designed for primary education.
PSK is one of three primary-grade formulas (with Spache and Dale-Chall). The three together provide consensus for elementary text. PSK is the simplest and fastest of the three.
Powers-Sumner-Kearl is a simplified Flesch variant from 1958: 0.0778 × avg sentence length + 0.0455 × syllables-per-100-words − 2.2029.
It outputs a grade level calibrated for primary education (grades 1-6).
Use alongside Spache and Dale-Chall for a primary-grade consensus.
Same inputs (sentence length + syllables) with different coefficients. PSK is calibrated for primary grades; FK extends through college.
For elementary text (grades 1-6), PSK is better calibrated. For older audiences, use Flesch-Kincaid.
In academic reading research, yes. In commercial writing, Flesch-Kincaid dominates. PSK shines as a third opinion for primary text.
Input
A 50-word elementary text with short sentences and one-syllable words.
Output
PSK grade 2.8 — primary.
Short sentences (avg 8 words) and low syllables-per-100 (110) place this firmly in early elementary range.
Classic 0–100 readability score.
readabilityU.S. grade level for your text.
readabilityPenalises complex (3+ syllable) words.
readabilityHealth & medical text grade level.