Short answer
Take your target grade, subtract your current grade multiplied by the share of the course that is already graded, then divide by the weight of the final. If you have 82% going into a final worth 30% and want 85% overall, you need 92% on the final.
Here Target is the course grade you want, Current is your grade on the work graded so far, and w is the final's weight as a decimal (30% = 0.30). If the result is above 100%, the target cannot be reached without extra credit.
1. Example: current 82%, final worth 30%
| Target course grade | Score needed on the final |
|---|---|
| 90% | 108.7% (not reachable) |
| 85% | 92.0% |
| 80% | 75.3% |
| 75% | 58.7% |
| 70% | 42.0% |
| 60% | 8.7% |
Notice how steeply the requirement rises. Moving from a 70% target to a 90% target does not add 20 points to the final; it adds about 67, because the final only controls 30% of the grade.
2. How the final's weight changes what you need
With a current grade of 75% and a target of 80%, here is how much the final's weight matters:
| Final exam weight | Score needed on the final |
|---|---|
| 20% | 100.0% |
| 25% | 95.0% |
| 30% | 91.7% |
| 40% | 87.5% |
| 50% | 85.0% |
3. Worked example with several categories
Suppose your syllabus weights homework 20%, quizzes 15%, the midterm 25%, a project 15% and the final 25%. You have 88 on homework, 79 on quizzes, 74 on the midterm and 91 on the project, and you want 80% overall.
- 1Points earned so far = 0.20 × 88 + 0.15 × 79 + 0.25 × 74 + 0.15 × 91 = 61.60.
- 2Points still needed = 80 − 61.60 = 18.40.
- 3Score on the final = 18.40 ÷ 0.25 = 73.6%.
This version works directly from the weighted points, so you do not need a single "current grade" figure.
4. Common mistakes
- Using the wrong current grade. Your current grade must be calculated only on the work already graded, not the whole course.
- Entering weights that don't add up. Check that all categories, including the final, total 100%.
- Forgetting dropped grades. If your instructor drops the lowest quiz, recalculate the current grade after the drop.
- Ignoring the cutoff. Confirm whether an A starts at 90 or 93 in your course and whether grades are rounded.
To run your own numbers, use the Final Grade Calculator. For a full weighted course grade use the Weighted Average Calculator, and to convert a grade to GPA use the GPA Calculator.
5. Frequently asked questions
How do I calculate what I need on my final exam?expand_more
Subtract your current grade multiplied by (1 minus the final's weight) from your target grade, then divide by the final's weight. For example, (85 − 82 × 0.70) ÷ 0.30 = 92%.
What if the score I need is over 100%?expand_more
It means the target can't be reached from the final alone. Ask whether extra credit exists, or choose the highest grade you can reach with a score of 100%.
Does a heavier final make it easier or harder?expand_more
A heavier final gives you more control over the outcome, so a lower score reaches the same target when your current grade is below it. If your current grade is above the target, a lighter final is easier.
What if my class drops the lowest score?expand_more
Recalculate your current grade after dropping that score, then apply the formula.
6. Sources
- menu_bookWeighted average definition: standard grade weighting used in syllabi; verify the weights and grading scale in your own course syllabus.
Check your syllabus for weights, rounding and grade cutoffs. This is an educational estimate.