Each semester or quarter, depending on how your school is set up, you will receive a report card. Some schools grade out of 100 percent, while some use a four-point scale for letter grades. You can calculate your yearly average by using an averaging formula that will provide you with your overall grade, or grade-point average for the entire year. Performing this calculation will also help you find if there has been a mistake.

Find all your grades for the year by gathering report cards or requesting the grades from your teacher.

Add together all your grades that are calculated on a percentage scale. Each grade will be a percentage of 100.

Divide your total points by the number of classes you took. For example, if your grades in five classes added up to 462, divide 462 by 5 to find that your yearly average is 92.4 percent.

Convert your average for each class to a letter grade if you want to find your average on a four point scale. The teacher should have an average to letter grade conversion in the class syllabus.

Match the letter grade with the corresponding four point grade. These may differ between schools, but you should check your school's course catalog for this information. Usually the conversions are 4.0 for an A, 3.6 for an A-, 3.3 for a B+, 3 for a B, 2.6 for a B-, 2.3 for a C+, 2 for a C, 1.6 for a D+, 1 for a D, and 0.6 for a D-. These are your quality points.

Multiply your quality points for each class by the number of credits the class was worth. Then add the amount for each class. These are your total quality points. For example, assume your quality points for your classes came to 16, 12, 12, 9, and 16. Your sum is 65.

Divide your total quality points by your total number of credit hours taken to find your GPA on a four point scale. In the example, assume you had 20 credit hours, so 65 divided by 20 equals a GPA of 3.25.