The Crawford Score, developed by Alan N. Crawford in 1989, calculates the grade level needed to understand Spanish text. Crawford chose two key factors for his study: the average length of sentences and the number of syllables in 100 words. He studied passages from elementary readers popular in the United States, Latin America, and Spain, each tailored to a specific grade level. By calculating the average and variation of these factors and using multiple regression analysis, he linked these textual features to appropriate grade levels. The formula is valid up to 6th grade.

You can match the score to this table:

Score	U.S. Grade Level	Spain's Equivalent	Student Age
1	1st Grade	1º Primaria (Primero)	6-7 years
2	2nd Grade	2º Primaria (Segundo)	7-8 years
3	3rd Grade	3º Primaria (Tercero)	8-9 years
4	4th Grade	4º Primaria (Cuarto)	9-10 years
5	5th Grade	5º Primaria (Quinto)	10-11 years
6	6th Grade	6º Primaria (Sexto)	11-12 years
7	7th Grade	1º ESO	12-13 years
8	8th Grade	2º ESO	13-14 years
9	9th Grade (Freshman)	3º ESO	14-15 years
10	10th Grade (Sophomore)	4º ESO	15-16 years
11	11th Grade (Junior)	1º Bachillerato	16-17 years
12	12th Grade (Senior)	2º Bachillerato	17-18 years
13	College	Universidad (University)	18+ years