Final Grade Calculator
Find out exactly what you need on the final exam to get the course grade you want
on the final to finish the course at 90.0%. That is above 100%, so the target is out of reach without extra credit — the best you can now finish with is 88.0% (B+).
What each final score gives you
| Score on the final | Course grade | Letter |
|---|---|---|
| 100% | 88.0% | B+ |
| 90% | 86.0% | B |
| 80% | 84.0% | B |
| 70% | 82.0% | B- |
| 60% | 80.0% | B- |
| 0% | 68.0% | D+ |
Letter cutoffs use a common US +/− scale. Yours are set by your school and syllabus.
The formula
needed = (target − current × (1 − w)) ÷ w
where w is the final’s share of the course grade as a decimal (a 20% final is 0.2), current is your average on everything else, and target is the course grade you want. The logic is simply that the non-final work is already locked in at current × (1 − w), so the final has to supply whatever is left to reach the target — and it only gets to contribute w of the total.
A worked example
You have an 85% going into the final. The final is worth 20% of the course, and you want an A− (90%).
- The other 80% of the course is locked in at 85 × 0.8 = 68 points.
- To finish at 90 you need 90 − 68 = 22 points from the final.
- The final only supplies 20% of the grade, so 22 ÷ 0.2 = 110%.
- Above 100 — so an A− is gone. Acing the final gives 68 + 20 = 88%, a B+.
This is the single most useful thing the calculator tells you, and it is the thing a simple “you need 110%” leaves out.
Mistakes that make the answer wrong
- Using a current grade that already counts the final as a zero. Portals often do this before the exam is marked, which drags the number down.
- Confusing the final’s weight with the exam category’s weight. If “Exams 50%” covers two midterms and a final, the final is not worth 50%.
- Forgetting dropped scores. If your syllabus drops the lowest quiz, your true current grade is higher than the raw average.
Related Calculators
Frequently Asked Questions
How do I calculate what I need on my final exam?
Use: needed = (target − current × (1 − final weight)) ÷ final weight. With an 85% current grade, a final worth 20%, and a 90% target: (90 − 85×0.8) ÷ 0.2 = 110%. Anything above 100% means the target is out of reach without extra credit.
What counts as my "current grade"?
Your average on everything except the final. If the grade in your school portal already includes the final as a zero, it is not the number to use here — that version treats the unsat exam as a fail and will read far too low.
What if my final is worth 0%?
Then it cannot change your grade at all, and no score on it will move you. This calculator says so instead of dividing by zero and printing NaN.
Can I still pass if I need more than 100%?
Not from the final alone. The calculator shows the best grade you can now finish with, so you can see the realistic ceiling and decide whether to ask about extra credit, a retake, or a late assignment.
Why does my school portal show a different number?
Most portals compute your grade over the work graded so far, while this asks what happens once the final is added. They also differ on dropped lowest scores, curved marks and extra credit, none of which this formula knows about.