Write a list of all the courses you have taken for your major. Include your grade in the course and the number of credits it was worth. For example, suppose an accounting student took a three-credit "Intro to Accounting" class and received an "A," a three-credit business class and received a "B" and a four-credit "Intermediate Accounting" class and got a "B+."

Change the grade in each course from a letter to a number. Each letter corresponds to a number, an "A" is 4, "B" is 3, "C" is 2, "D" is 1 and "F" is 0. Add 0.33 to the grade if you got a "+." Subtract 0.34 if you got a "-." In the example, an"A" is a 4, a "B" is a 3 and a "B+" is a 3.33.

Multiply the corresponding number grade by the number of credit hours the class was worth. In the example, 4 times 3 equals 12, 3 times 3 equals 9, and 3.33 times 4 equals 13.32. These are known as quality points. Your major quality points then are 12, 9 and 13.32.

Add together the quality points from your major. In the example, 12 plus 9 plus 13.32 equals 34.32.

Add together your credit hours taken. In the example, 3 plus 3 plus 4 equals 10.

Divide your major's quality points by the total major credit hours. In the example, 34.32 divided by 10 equals 3.432 GPA.