How to Calculate an Average Grade

By Andrea Hamilton; Updated April 24, 2017
Calculating their grades helps students know where they stand in class.

When taking a course, it is unsettling to remain in the dark about your grade, especially if the instructor does not provide students with regular updates. An average grade in the American public school system is a C, which is quantified as being a percentage of or between the scores of 70% and 79%. By calculating your personal average score, you can discover whether your grade ranks above, below or on the average.

Calculating a Personal Average

Tallying up all of the assignments will help you know what number to divide by later.

Collect all of the semester's assignments. Convert their scores to a common denominator. If the scores are all percentages of 100, this has been done already. If they are weighted by being scored out of different points, skip to Section 2. If some of your assignments are missing, the result will be skewed.

Add all of the scores together. If you have completed 10 assignments this semester and received 90% on each of them, your score is 900 out of 100%.

Divide the sum of your score (900) by the number of assignments you completed this semester (10). The quotient in decimal form is your average grade. In the example, with 10 assignments completed and each scoring 90%, the average score is 90%. Failing to complete an assignment brings down your average more than earning a poor mark.

Calculating Averages for Weighted Scores

Add the denominators (the bottom numbers) in all of the assignments' fractions, ignoring their numerators. If you have four assignments scored out of 12, 10, 7 and 5 points, the total possible points is 34.

Add the numerators (the top numbers) of the fractions. If, for example, you missed only two points on all of the assignments, your result will be 32/34.

Divide the top number by the bottom number to receive either a 1 (for 100%) or a decimal for anything lower. The first two digits of the decimal are your average percentage. In this example, 32 divided by 34 is .94 or 94%.

About the Author

Andrea Hamilton has enjoyed being a writer since 1996. She has been published as a poet in "Fine Lines Magazine." Hamilton holds a Bachelor of Arts in literature from Iowa State University and is pursuing a Master of Arts in creative writing from London South Bank University.