What Do I Need on My Final? Formula and Examples
Your final is worth a fixed share of your grade, so the score you need is simple arithmetic. Here's the formula, three worked examples and the edge cases syllabi hide.
Most courses give the final exam a fixed share of your grade: 20%, 25%, sometimes 40% or more. That makes the score you need on the final a short calculation, not a guess. You only need three numbers, and you can usually find all of them in ten minutes.
The three numbers you need
- Your current grade. Your percentage in the course right now, based on everything graded so far. Most learning platforms (Canvas, Blackboard, Moodle, Google Classroom) show it on the grades page.
- The final's weight. How much of your total course grade the final is worth. It is almost always in the syllabus, for example "Final exam: 25%".
- Your target grade. The overall percentage you want to finish the course with, such as 90 for an A- or 80 for a B- on a common US scale.
Letter grade cutoffs are not universal. Some courses give an A at 90%, others at 93%, and some round 89.5 up while others don't. Use the cutoff in your syllabus, not a generic chart.
The formula
Score needed on the final = (Target − Current × (1 − Weight)) ÷ Weight
Write the weight as a decimal: 25% becomes 0.25. The idea is simple. Your current grade covers the part of the course that isn't the final (75% of it in this case), and the final covers the rest. The formula asks what the final has to be for the two parts to add up to your target.
Three worked examples
1. Holding on to a B-
You have 82%, the final is worth 25%, and you want to finish with at least 80%.
(80 − 82 × 0.75) ÷ 0.25 = (80 − 61.5) ÷ 0.25 = 74% on the final.
2. Reaching for an A-
Same course, but now you want 90%.
(90 − 61.5) ÷ 0.25 = 114%. That isn't possible through the final alone, so the realistic goal is the grade below, unless the course offers something extra (more on that below).
3. A heavy final
You have 71%, the final is worth 40%, and you need 73% for a C.
(73 − 71 × 0.6) ÷ 0.4 = (73 − 42.6) ÷ 0.4 = 76% on the final.
How the final's weight changes everything
The weight decides how far the final can move your grade. A heavy final gives you room to climb; a light one mostly protects what you already have. Here is what a student at 85% needs to finish with 90%:
| Final weight | Score needed for 90% |
|---|---|
| 20% | 110% (not possible) |
| 30% | 101.7% (not possible) |
| 40% | 97.5% |
| 50% | 95% |
And here is what a student already at 92% needs to stay at or above 90%:
| Final weight | Score needed to keep 90% |
|---|---|
| 20% | 82% |
| 30% | 85.3% |
| 40% | 87% |
The pattern holds in every course: when you are below your target, a heavier final helps; when you are above it, a heavier final means more is at stake.
When the simple formula doesn't fit your course
- Points instead of percentages. If your syllabus counts points, the final's weight is its points divided by the course's total points (100 out of 500 is 0.2). Your current grade is the points you've earned divided by the points possible so far.
- Work still to be graded. The formula assumes everything except the final is finished. If a project or homework set is still outstanding, your current grade will move. Run the numbers again once it's graded.
- The final replaces a low score. Some instructors drop your lowest exam or let the final replace it. In that case a strong final counts for more than its listed weight, and the formula is a conservative estimate.
- A minimum score on the final. Some courses require a passing mark on the final itself, whatever your average. If yours does, aim for whichever number is higher.
- Curves and rounding. A curve or a generous rounding rule can lower the real target. Don't count on either unless the syllabus promises it.
Doing it in seconds
If you'd rather not do the arithmetic, the final grade calculator uses exactly the formula above:
- Enter your current grade as a percentage, for example 82.
- Enter how much the final is worth, for example 25.
- Pick your target from the list (A is 93%, A- 90%, B+ 87%, B 83%, B- 80% and so on), or choose Custom % to use your syllabus's own cutoff.
- It shows the score you need on the final, or Not possible when the target would take more than 100%.
It runs in your browser and doesn't store anything you type.
What to do with your number
- Under about 70%: your target is within easy reach. Steady review is enough, and you can give more time to courses that need it.
- Between 70% and 85%: normal, focused preparation. Practice exams and past papers matter most here.
- Above 85%: this course should get priority in your study schedule. Start early and work on your weakest topics first.
- Over 100%: the target isn't reachable through the final alone. Ask your instructor about extra credit or a dropped score, and plan around the next grade down rather than an impossible one.
Once you know what each course will end up as, the semester GPA calculator shows what those grades do to your GPA for the term.
Frequently asked questions
What if I need more than 100% on my final?
Then that target can't be reached through the final alone. Check whether your course offers extra credit, drops a lowest score or lets the final replace a low exam; otherwise plan around the next grade down.
Is the final's weight a share of points or of the grade?
The formula uses its share of your total grade. In a points-based course, divide the final's points by the course's total points to get the weight, for example 100 out of 500 is 20%.
What should I use as my current grade if work is still ungraded?
Use your grade on everything graded so far, then recalculate once the remaining work is marked, because your current grade will change.