Record each percentage score that your student receives so that you can easily retrieve it later. You may use all the student's assignments and tests to calculate the overall course score or use only the test scores. If you include both assignments and tests, you can give tests more weight by having double the questions on tests than assignments.
Add the scores your student received and divide the total by the total score the student could have received. For example, if the course consisted of four graded tests and the student received 16 out of 20, 17 out of 20, 18 out of 20 and 19 out of 20, the total for the course would be 70 out of 80, or 87.5 percent.
Translate the student's score into a letter grade for the course. In the above example, the student would receive a B for the course if 90 to 100 percent is an A and 80 to 90 percent is a B.
Assign the letter score a numerical value from 0 to 4, with 0 being an F and 4 being an A. In this case, the course would be scored a 4 because the student received a B.
Tally the numerical values for every course and divide the total by the total number of courses. This will be your student's GPA. For example, if a student is taking five courses and receives two A's, two B's and a C, his GPA is 3.2. This is because the two A courses would total 8, the two B courses would total 6 and the C course would get a 2, for a total of 16. Divide 16 by the number of courses, which is five, to arrive at 3.2.
Calculate your student's GPA regularly to keep up with how he is doing and ensure that he is staying on track for acceptance into the college of his choice.