Gutiérrez de Polini's Readability Formula (Fórmula de Comprensibilidad de Gutiérrez de Polini), created by Luisa Elena Gutiérrez de Polini, is an original formula to score the readability of Spanish text. The formula counts syllables, words, and sentences and outputs a score that correlates with a reading scale. The formula is as follows:

• C is the total number of syllables in the text
• W is the total number of words,
• Snt is the total number of sentences.

The formula addresses Spanish syntax and morphology, which are different from English and other languages. This makes it a valuable tool for educators, writers, and linguists who are working with Spanish-language materials.

Gutiérrez de Polini published the formula in a thesis titled "Investigación sobre lectura en Venezuela" and presented it at the "Primeras Jornadas de Educación Primaria" in Caracas, Venezuela, in 1972, under the auspices of the Ministry of Education.

I couldn't find the formula's readability scale so I created this one, which aligns with common "reading ease" and "reading difficulty" results of other formulas.

Gutierrez Interpretation	English Grade	Age Range	G Score Range	Spanish Grade
Very Difficult	College and Above	19+ year olds	<= 20	Universidad y superior
Difficult	11th - 12th Grade	16-18 year olds	<= 33	1º - 2º Bachillerato
Slightly Difficult	9th - 10th Grade	14-16 year olds	<= 40	3º - 4º ESO
Average	7th - 8th Grade	12-14 year olds	<= 50	1º - 2º ESO
Slightly Easy	5th - 6th Grade	10-11 year olds	<= 60	5º - 6º Primaria
Easy	3rd - 4th Grade	8-9 year olds	<= 70	3º - 4º Primaria
Very Easy	1st - 2nd Grade	6-7 year olds	> 70	1º - 2º Primaria

Gutiérrez de Polini originally developed the formula to score texts up to 6th grade, but the above table projects the results beyond the original data.