Each category counts by its weight, not equally
A weighted grade multiplies every category score by its share of the course, adds them up, and divides by the total weight. When the weights already add to 100%, that division is just the sum.
Homework 85 at 20%, quizzes 90 at 30%, final 78 at 50%: (85×0.20) + (90×0.30) + (78×0.50) = 17 + 27 + 39 = 83%. A plain average of the three would read 84.3% — the difference is the heavy final pulling the grade down.
Turn a percentage into a letter and GPA point
| Percent | Letter | GPA | Percent | Letter | GPA |
|---|---|---|---|---|---|
| 93–100 | A | 4.0 | 73–76 | C | 2.0 |
| 90–92 | A− | 3.7 | 70–72 | C− | 1.7 |
| 87–89 | B+ | 3.3 | 67–69 | D+ | 1.3 |
| 83–86 | B | 3.0 | 63–66 | D | 1.0 |
| 80–82 | B− | 2.7 | 60–62 | D− | 0.7 |
| 77–79 | C+ | 2.3 | <60 | F | 0.0 |
This is the common US 4.0 scale. Some schools award an A+ at 4.3 and shift the cutoffs by a point or two, so confirm against your syllabus.
Weights must add to 100%, or the math skews
- Missing weight. If your categories only sum to 90%, dividing by the true weight total (not 100) keeps the grade honest until the last category is entered.
- Empty categories. A category with no scores yet should be left out of the weight sum, not counted as a zero — otherwise your grade looks far worse than it is.
- Target above 100%. If the score you would need on the final comes out over 100, the target is out of reach with the points remaining.
Common questions
How do I calculate a weighted grade by hand?
Multiply each category score by its weight, add those together, then divide by the sum of the weights. If homework is 85 at 20%, quizzes 90 at 30%, and the exam 78 at 50%, the grade is 85 times 0.20 plus 90 times 0.30 plus 78 times 0.50, which is 83%.
What does it mean that the final exam is worth 40%?
The final counts for 40% of your course grade. The other 60% comes from everything else. A high weight means that one score moves your grade far more than a low-weight assignment does.
What score do I need on the final to reach my target?
Subtract your current grade times the non-final weight from your target, then divide by the final weight. If your target is 90, your current grade is 85, and the final is 40% of the course, you need (90 minus 85 times 0.60) divided by 0.40, which is 97.5%.
