Change your letter grades to a grade point. Your school may provide number equivalents, or you can use the following values:
A = 4.0
A- = 3.7
B+ = 3.3
B = 3.0
B = 2.7
C+ = 2.3
C = 2
C- = 1.7
D+ = 1.3
D = 1.0
D- = 0.7
F = 0
Multiply the grade point earned in each class by the number of credits assigned to the class. For example, if you enrolled in three course each worth three credits and received an A-, C+ and B in these courses, the calculation would be as follows:
English: 3.7 x 3 = 11.1
Math: 2.3 x 3 = 6.9
Science: 3 x 3 = 9
Calculate the sum total of each grade point that you earned. Using the previous example, you would calculate the total for all three course: 11.1 + 6.9 + 9 = 27.
Divide the total grade points earned by the number of credits attempted. In the example, divide 27 (total grade points) by 9 (number of credits) to arrive at a 3.0 GPA.