How to Calculate Your Final Grade
Two questions, one formula rearranged. What grade will I finish with, and what do I need on the final to reach the grade I want?
The short answer
Final grade = current grade × (1 − weight) + exam score × weight.
Rearranged for the score you need: (target − current × (1 − weight)) ÷ weight. Weight is the final's share of your grade as a decimal, so 25% is 0.25. If the answer comes out above 100, the target cannot be reached.
What the formula is doing
Think of your course grade as a hundred points waiting to be allocated. If the final is worth 25%, then 75 of those points have already been decided by your work so far and 25 are still on the table.
Final grade = banked + exam score × weight
Score needed = (target − banked) ÷ weight
"Banked" is the useful intermediate. Once you have it, both questions are one step away, and it makes clear why the answers behave as they do — the banked portion cannot change, so everything depends on how much the remaining weight can add.
Direction one: the grade you will finish with
You have an 84% in the course and the final is worth 30%. That banks 84 × 0.70 = 58.8 points, and leaves 30 on the table.
Score 92% on the final and you finish with 58.8 + 92 × 0.30 = 58.8 + 27.6 = 86.4%.
Across the whole range of possible exam scores:
| Score on the final | Final course grade | Letter | Change |
|---|---|---|---|
| 100% | 88.8% | B+ | +4.8 |
| 90% | 85.8% | B | +1.8 |
| 84% | 84.0% | B | no change |
| 80% | 82.8% | B− | −1.2 |
| 70% | 79.8% | C+ | −4.2 |
| 60% | 76.8% | C | −7.2 |
| 0% | 58.8% | F | −25.2 |
The highlighted row is worth internalising: the score that leaves your grade unchanged is exactly your current grade. Score above it and you go up, below it and you go down. That holds whatever the final is worth — the weight changes how far you move, never which direction.
Direction two: the score you need
Same student, aiming for a B at 85%:
- Banked: 84 × 0.70 = 58.8
- Still needed: 85 − 58.8 = 26.2 points
- From a final worth 30 points: 26.2 ÷ 0.30 = 87.33%
So an 87.33% on the final gets them to exactly 85%. Anything higher gives margin.
Run both directions
Enter your current grade and what the final is worth. Ask for the score you need, or for the grade a given score would leave you with.
Open the Final Grade CalculatorWhen the target is out of reach
Push the target to an A at 90% and the arithmetic turns:
- Still needed: 90 − 58.8 = 31.2 points
- From a final worth 30 points: 31.2 ÷ 0.30 = 104%
The final can supply at most 30 points and 31.2 are required. A 104% is not a hard target, it is an impossible one: the best this student can finish with is 58.8 + 30 = 88.8%, even with a perfect exam.
A number above 100% is the answer, not an error
Some calculators print the figure without comment and leave you to work out that it cannot be done. The version here says so directly and shows the best grade still available, because finding out before the exam leaves you options — extra credit, a curve, or aiming at the grade that is still in play — and finding out afterwards does not.
The same arithmetic runs the other way. The worst this student can finish with is 58.8%, so if they need a 60% to pass, even a zero on the final is not quite survivable — which is worth knowing with the same urgency.
How much the weight matters
The final's weight sets how far your grade can move. Starting from 84%:
| Final is worth | Best possible | Worst possible | Range |
|---|---|---|---|
| 10% | 85.6% | 75.6% | 10 points |
| 20% | 87.2% | 67.2% | 20 points |
| 30% | 88.8% | 58.8% | 30 points |
| 40% | 90.4% | 50.4% | 40 points |
| 50% | 92.0% | 42.0% | 50 points |
A lightly weighted final is safe and also useless — at 10% it cannot lift an 84% out of the B range however well you do. A heavily weighted one is the only thing that can reach an A, and the only thing that can produce a failing grade. The range is always exactly the weight.
Common mistakes
- Using a current grade that counts the final as zero. The single biggest source of wrong answers here. Enter your standing on graded work only.
- Entering the weight as a whole number in the formula. Multiply by 0.30, not 30, or divide by 100 afterwards.
- Forgetting that a cumulative final is still one weight. A final covering the whole course is worth whatever the syllabus says, regardless of how much material it examines.
- Treating a multi-part final as separate. If a paper and an exam are graded together as the final, use their combined weight.
- Aiming at the rounding. Targeting 89.5% and hoping for an A− is a bet on a policy you may not have in writing.
Limits
- Curves and extra credit are applied afterwards and cannot be predicted from these figures.
- Some courses require a minimum final exam score to pass, independently of the course average. That is a rule the formula knows nothing about.
- Dropped scores — a policy that drops your lowest test — change your current grade before any of this applies.
- These are planning numbers. Your instructor's gradebook is the record, and a discrepancy is worth raising before the final rather than after.
Frequently asked questions
What score do I need to pass?
Use the required-score formula with your passing threshold as the target. If your course needs a 60% overall and you are at 68% with a final worth 25%, you need (60 − 68 × 0.75) ÷ 0.25 = 36%. Some courses also set a minimum exam score independently of the average; check the syllabus.
How do I find what my final is worth?
The syllabus, usually in a grading breakdown. If it lists points rather than percentages, divide the final's points by the total points available in the course — a 200-point final in an 800-point course is worth 25%.
What if my final replaces my lowest test?
Then the weight depends on the outcome, and the formula cannot be applied directly. Work out both scenarios — the final as its own category, and the final substituted for the low test — and use whichever your syllabus says applies.
Does the current grade include the final as a zero?
It should not. Enter your standing on graded work only. Many gradebooks display a figure that treats ungraded categories as zeros, which will make the calculation badly wrong. The weighted grade calculator will give you the correct starting figure.
Can my instructor round up?
Some do, some do not, and some round only at specific boundaries. It is a policy question rather than an arithmetic one, and worth asking early rather than counting on.
Calculators for this
Final Grade Calculator
Find the score you need on the final exam, or the course grade a given final score will give you.
Grade Calculator
Add up points earned and points possible across assignments to get your course percentage and letter grade.
Weighted Grade Calculator
Calculate a course grade where homework, tests and projects each count for a different percentage.
Read next
-
How to Calculate Weighted Grades
Turning a syllabus of percentages into a course grade, including what to do when your categories do not add up to 100%.
Your school sets the rules this guide describes, and schools differ. Your syllabus, transcript and registrar are the authoritative source for your own record.