How to calculate what you need on the final exam
The final grade in a course is almost always a weighted average of several components: homework, quizzes, assignments and a final exam, where each component has a weight in percent and the weights add up to 100%. The points that are already “locked in” are the sum of what you have collected so far, meaning each grade multiplied by its weight. All that is left to find out is what you need on the last component (the final exam) to reach your target grade.
The formula is simple:
required exam grade = (target grade − points you already have) ÷ (exam weight ÷ 100)
“Points you already have” are calculated like this: for each component that has a grade, multiply the grade by its weight (in percent, meaning weight divided by 100), and add them up. This is exactly the same logic as calculating a weighted average, only solved “backwards” to find the missing grade instead of the average.
A worked example, step by step
Say you have a course with the components below, and you want to finish it with a grade of 80:
| Component | Weight | Grade | Points earned (grade × weight) |
|---|---|---|---|
| Homework | 30% | 85 | 25.5 |
| Midterm quiz | 20% | 70 | 14.0 |
| Final exam | 50% | ? | ? |
| Total earned so far | - | - | 39.5 |
You have already earned 39.5 points toward the 80 you want, so 40.5 points still have to come from the final exam. The exam is worth 50%, so you divide: 40.5 ÷ 0.5 = 81. In other words, you need at least 81 on the final exam to finish the course with 80. Notice that the grade you need (81) is higher than 80 itself, because the earlier components (especially the quiz, at 70) pulled your grade down, and the final exam has to make up for it.
To see what you need in order to pass, enter your school’s passing grade as the target. Passing grades differ between schools and courses, so check yours in the syllabus or regulations.
What if you need more than 100?
Sometimes the calculator will show that to reach your target you would need over 100 on the exam. That means it is mathematically impossible, even with a perfect score. It is a sign that the target you set is too high relative to what you have already earned. A few practical options:
- Set a more realistic target. Check the highest grade you can still reach (enter 100 on the exam and see what comes out for the course).
- Check for other open components. If there is still an assignment, a bonus for participation or a homework to submit, those count too and can still improve your result.
- Ask your instructor. Find out whether there is a second exam sitting, a bonus question or an alternative weighting. Sometimes the regulations allow more flexibility than it seems.
What you need in remaining courses to reach a target average
The question “What do I need?” also comes up at the level of the whole degree, not only a single course: What grades do I need in my remaining courses to raise my average to 85? The “Average for remaining courses” tab in the calculator above does exactly this calculation. Enter your current average, how many credits you have earned, how many are left, and the average you want for your degree, and it works out the average you need going forward. If you want to track this over time with all your real courses, move on to the weighted average guide and the full tool.
Why use an automatic tool instead of doing it by hand
For a one-time calculation for a single course, the formula above is enough. But when you want to manage all your courses, test scenarios (“What happens to my average if I get 90 in this course?”) and track targets across your degree, it is better to use a tool that does it automatically and without errors. You can manage your average and targets in the app here for free, with no sign-up, and your data stays in your browser.