An average does not get converted directly into a GPA. Each course’s letter grade gets converted into a number out of 4. The standard conversion is: A = 4, B = 3, C = 2, D = 1. An A minus is 3.7 (or maybe 3.66). A B+ is 3.3 (or maybe 3.33). Add up the GPA for each course, divide by the number of course and you have your cumulative GPA (or cGPA). What percentage corresponds to an A or B or B minus depends on your high school. That’s the standard conversion. Some university admissions departments may calculate it differently. For some high schools, a 90.7% may be a 4.0, for others it might be a 3.5.