How this calculator works
Each component grade is multiplied by its weight, the products are added and the total is divided by the sum of the weights. If the weights are 40, 40 and 20, the two quarters carry 40 percent each and the exam carries 20 percent. Dividing by the weight total means the weights do not have to add to exactly 100; 4, 4 and 2 give the same result. Bonus points are added after the weighted average, in percentage points, because they usually apply to the final semester mark rather than to one component.
Formula
weighted average = (q1 x w1 + q2 x w2 + exam x we) / (w1 + w2 + we). Semester grade = weighted average + bonus points / 100. Weights are entered as percentages and converted to fractions.
Worked example
Quarter grades of 85 and 88 with a semester exam of 80, weighted 40, 40 and 20, give (85 x 0.40 + 88 x 0.40 + 80 x 0.20) / 1.00 = 34 + 35.2 + 16 = 85.2 percent. Two bonus points raise the semester grade to 87.2 percent, which moves the letter grade from a B to a B+ on the scale used here.
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Frequently asked questions
Do the weights have to add to 100?
No. The calculator divides by the sum of the weights, so 40, 40 and 20 and 4, 4 and 2 produce the same grade. This is useful when a school quotes weights as fractions or when one component is temporarily missing.
How are bonus points different from extra credit?
Bonus points here are added directly to the semester percentage after weighting. Extra credit usually adds points to an assignment or raises a component grade before weighting, which has a smaller effect. Add the extra credit to the component grade first if that is how your teacher records it.
What if my school uses three quarters?
Combine the first two quarters into one entry using their own weights, or use the grade calculator with one row per component. This page is built around the common two-quarter plus exam structure.
Why is the letter grade shown with a different scale than my school?
The letter is a common percentage scale, not a universal rule. Some schools start an A at 90 and others at 93, and some do not use plus or minus grades. The percentage is the exact result; the letter is a guide.