How to Calculate Grades Based on Percentages

by Helen Jody Lin

Many teachers weight homework, quizzes and tests grades differently depending on the difficulty and significance of the assignment. Big tests and quizzes generally account for most of the total grade because they encompass more of the subject material. Whether you are on the verge of failing a class or just want to know how your grades add up, you can calculate your grades with a few simple formulas.

Establish your professor's grading policy for how each category is weighted. For example, the professor may weigh 35 percent of the final grade to quizzes, 20 percent to homework and 45 percent to tests.

Calculate the average of each category by adding up all the scores for each category and divide by the number of assignments in that category. For example, if you have five tests with the scores of 90, 85, 100, 75 and 91, the accumulated point total for all your test would be 441. Divide the total by five for your test average of 88.2 percent.

Convert the weighted grade percentages to decimal value by dividing the percentage by 100. For example, if tests are weighted 45 percent of the total grade, the decimal would be 0.45 (45 / 100 = 0.45). Repeat this step for each weighted section (homework, quizzes, tests, etc.).

Multiply the average for each category by the weight, in decimal, of each category to calculate the final points out of 100. For example, if your test average is 88.2 percent and is weighted 45 percent, the points for your overall grade out of 100 would be 39.69 (which is 88.2 x 0.45). Repeat this step for your other categories.

Add the results for each category from Step 4 to find out your total grade out of 100 points. For example, if you calculated a 39.69 for test, 34 for quizzes and 18.5 for homework, your total grade would be 92.19 percent.

Things You Will Need

  • Calculator

About the Author

Helen Jody Lin has been writing since 2009. She has written screenplays, produced short films and worked in entertainment marketing. Her work has been published in campaigns for Fanscape, a digital media marketing agency. Lin has a thorough knowledge of broad topics such as fitness and extreme sports. She graduated from the University of Texas at Austin with a Bachelor of Arts in radio-television-film.