The Spache Readability Formula scores text against a list of familiar primary-grade words. Designed for K-4 reading material.
Use Spache for any text aimed at K-4 readers — primary readers, beginning ESL, picture books, learn-to-read content. It's the formula educators most often request for grade 4 and below.
Spache and Dale-Chall both use familiar-words lists, but Spache targets younger readers (K-4) and Dale-Chall targets grades 4+. Use Spache for primary, Dale-Chall for everything else.
The Spache Readability Formula was developed in 1953 specifically for primary-grade text (K-4).
It scores against a list of approximately 1,000 words familiar to elementary readers, combined with sentence length: grade = 0.121 × avg sentence length + 0.082 × % unfamiliar + 0.659.
Best used to evaluate beginning readers, picture books, and ESL primary material. Above grade 4, switch to Dale-Chall.
Spache for K-4 reading material. Dale-Chall for grade 4+. They use different familiar-words lists.
The Spache list dates to 1953 — modern children's vocabulary may not match. Suffix stripping helps but isn't perfect.
Grade 1-2 for early readers, 3-4 for primary independent reading. Above grade 4, use a different formula.
Input
"The dog ran fast across the green field."
Output
Spache grade 1.4 — primary.
All eight words are in the Spache familiar-words list and the sentence is short. Suitable for grade 1–2 readers.
Classic 0–100 readability score.
readabilityU.S. grade level for your text.
readabilityPenalises complex (3+ syllable) words.
readabilityHealth & medical text grade level.