High School students, use this calculator to estimate the outcome of this semester's grades on your overall average. To calculate your cumulative average, enter in your current GPA and number of classes from previous semesters; then this semester's grades and credits. If you are taking AP, honors or college preporatory classes, select the corresponding class type to calculate your weighted GPA. This calculator uses a standard scale where an regular class A is worth 4.0 points. An AP/Honors A is worth 4.5 and a College Prep A is worth 5.0 grade points.