Collect the grades from which you wish to calculate your GPA. You can find them by using past report cards or you can use your recent assignments if you want to calculate the grade for your current classes.
Convert the grades into grade points. Each letter grade is worth a certain number of points. An A is worth four points, a B is worth three points, a C is worth two points and a D is worth one. An F or incomplete grade does not add any points to your score. Once you have the numerical score for each individual grade, add them up.
Add up the number of credit hours you have taken. Calculate your average by dividing the total number of grade points you accumulated by the number of credit hours you took during the same period, including any F's you received. The hours from Incomplete grades do not count toward either total.