Gradebook subtotals are calculated by taking the number of points a Student earned divided by the number of points available to be earned.
If the Gradebook has Weighted Categories, after determining the subtotal for the Category by taking points earned out of points available, the Category weights are used to come up with the Subtotal.
Simple Gradebook (no Categories)
In a Simple setup--a Gradebook that does not use Categories--all entries are averaged to find the final grade.
A Gradebook has four entries with the following values for one Student: 80/100, 70/100, 40/50, 6/10. The Student's final grade will be calculated by adding points earned (80+70+40+6), then dividing by points available (100+100+50+10). So, in this case, the Student's grade is 196/260, or 75%.
Gradebook with Categories (not weighted)
In a Gradebook with Categories that are not weighted, the final grade calculation is exactly the same as in the Simple setup. All entries are averaged to get the Final Grade.
Gradebook with Weighted Categories
In a Gradebook with Weighted Categories, all entries in each category are averaged (by taking, as above, the points earned out of the points available), then all categories are averaged together according to their weight.
Category 1 (25%): ((90/100)*.25)=.225
Category 2 (75%): ((80/100)*.75)=.60
Category 1 (.225) + Category 2 (.60) = .825 = 82.5%
These are just the most basic Gradebook setups. If you'd like to read more in-depth details about Gradebooks with Finals, Class Schedules, Extra Credit, and more, please download the attached PDF.