Some teachers create different categories of grades to place more or less emphasis on certain assignments. For example, many teachers believe that tests should have a significant impact on your grade. However, because most classes have relatively few tests, teachers have to weight the test grades to make them have a bigger impact on your grade. For example, a teacher might make tests count for 50 percent of your grade and homework count for 50 percent, so even though you have 10 homework assignments and only two tests, those two tests still account for half of your grade.

Add the total number of points you earned on your tests. For example, if you got a 90, a 78 and an 85, you would add 90 plus 78 plus 85 to get 253.

Add the total number of points you could have earned on each test. For example, if all three tests were out of 100 points, you would add 100 plus 100 plus 100 to get 300.

Divide the result from Step 1 by the result from Step 2 to find your test average. Finishing the example, you would divide 253 by 300 to get 0.8433, or an average of 84.33 percent.