Use addition and division to calculate your grade on an individual assignment or test, your progress in class and your final class grade. For weighted grading systems, you'll also have to multiply assignment or class scores by the assigned weight. If assignments come with different point values, each one will be worth a specific percentage of your overall grade. In that case, some assignments will count more toward your class grade than others will. Follow these steps for both straightforward and weighted point systems.
Calculate the percentage you earned on one specific grade. To do this, take the total number of points you earned on the assignment and divide by the number of points the assignment was worth. If, for example, you earned 38 points out of a total possible 50 points, then your percentage is 76, as shown here: 38 / 50 = .76 or 76 percent. This is generally considered to be a "C" grade on a standard grading scale.
Determine the percentage of a class grade for one specific assignment. For this, you will need to take the possible points for every assignment in the class and add them together, and then divide the possible points for the specific assignment in question by the possible points for the course. If, for instance, a course has a total of 1,000 possible points and yesterday's test was worth 200 points, then you would divide 200 by 1000. That means that yesterday's test would be worth 20 percent of your overall grade in the course.
Find your overall grade in the class. Take the number of points you have earned on every assignment and add them together. Then divide this number by the number of possible points in the entire course. So if, for instance, you have earned 850 points total in a class where there were 1,000 possible points, your grade percentage in that class is 85. This is considered a "B" grade on an average grade scale.
Calculate your average for each weighted category. When grades are weighted, it means your teacher has assigned a specific percentage of your overall grade to each grade category. For this example, suppose your test grades are worth 50 percent, your homework grades are worth 25 percent, and your classwork grades are worth 25 percent of your overall class grade. The first step is to calculate your average score in each of these categories. Add up the total points you earned in each category and divide by the total points possible in each category.
Multiply the average grades you have for each category by the weight of that category. For this example, multiply your test score average by .50, your homework average by .25 and your class work average by .25. Suppose you earned 85 percent average on your tests, 90 percent average on your homework and 95 percent average on your class work, then the numbers you would have would be 42.5 (tests), 22.5 (homework) and 23.75 (class work). To calculate the weighted test score, multiply 85 percent by 0.50 to yield 42.5. Follow the same rationale in the formula to calculate the weighted scores for homework and class work. To calculate the weighted homework score, multiply 90 percent by .25 to yield 22.5. To calculate the weighted class work score, multiply 95 percent by .25 to yield 23.75.
Add the final figures together to determine your overall grade. If you add 42.5 with 22.5 and 23.75, you get 88.75. This means that your overall grade in this class is 88.75 percent, which is a high B average.
TL;DR (Too Long; Didn't Read)
If your teacher gives out letter grades instead of numerical grades, ask her to tell you the numerical equivalent of your grade. If you earn a B on a project, for instance, you need to know if she will use an 82 or an 88, or any other number, to calculate that grade as part of your overall average.