Colleges use many criteria to evaluate applicants, but two of the most important, and most easily quantifiable, are Grade Point Average (GPA) and Scholastic Assessment Test (SAT) scores. The GPA is calculated on a four-point scale and is based on a student's grades in his high school courses. The SAT is divided into three 800-point sections (reading, writing and math) for a maximum total of 2400 points. While GPA and SAT scores measure distinct aspects of academic performance, and can't be directly converted into each other, you can apply one to the scoring scale of the other for purposes of comparison.
Divide your GPA by the maximum GPA, which is 4.0. For example, if your GPA is 3.0, divide it by 4.0 to get .75.
Multiply .75 by the maximum possible score on the SAT, which is 2400 (800 for each of the three parts reading, math and writing).
Use the result to determine your "converted" SAT score. For example, if you computed .75 in Step 1, and multiplied that by the maximum SAT score, you would get a hypothetical SAT score of 1800.