Calculate your average grade for each category by adding all of your scores and dividing the sum by the number of items. For example, if you have 3 quizzes with the scores 78, 84 and 90, add them together, then divide the sum by three.
78 + 84 + 90 = 252.
252 / 3 = 84
Eighty-four is your average for the quizzes. Repeat the same process to find the averages of the other categories.
Multiply the averages by their relative percentages. For example, if quizzes are worth 30 percent of your grade, find the weighted score for the quiz by multiplying the average quiz score by its percentage.
84 x 0.30 = 25.2
The weighted scores for your quizzes is 25.2. Now, repeat this process for the other categories.
Add together all of your weighted scored to find the total weighted average. For example, if your weighted score for the quizzes was 25.2, the weighted score for the homework was 18.8, and the weighted score for the tests was 41, add those numbers together and you will find your total weighted average.
25.2 + 18.8 + 42 = 84.
Your average is 84 percent, and that is your total grade for the course.