How the final exam math works
Before the final, part of your grade is already decided. If the final is worth 20%, the other 80% is everything you have done so far, and your current grade tells you how well that went. The final fills in the last 20%.
Write the weight as a decimal: 20% is 0.20. The result is the percentage you need on the final exam itself.
Two examples
Close to the line. You have a 78 and want an 80 (a B-). The final is worth 25%. The locked-in part is 78 × 0.75 = 58.5. You need 80 − 58.5 = 21.5 more points from the final, and 21.5 ÷ 0.25 = 86%.
Out of reach. You have an 85 and want a 90, but the final is only worth 20%. The locked-in part is 85 × 0.8 = 68, so you need 22 points from a final worth 20: that is 110%. A perfect score would take you to 88, a B+.
How much a final can move your grade
The heavier the final, the more it can help or hurt. Starting from an 80 in the class:
| Final weight | Grade if you score 100% | Grade if you score 50% |
|---|---|---|
| 10% | 82.0 | 77.0 |
| 20% | 84.0 | 74.0 |
| 25% | 85.0 | 72.5 |
| 30% | 86.0 | 71.0 |
| 40% | 88.0 | 68.0 |
With a 10% final your grade barely moves, so it may be worth putting your study time into another class. With a 40% final, the exam decides most of the outcome.
How much is a final worth?
Check the syllabus first. The weight is usually listed with the other categories (“Final exam: 20%”), the same groups a gradebook like Canvas uses to weight the final course grade. If your class runs on points, divide the final’s points by the course total: a 200-point final in a 1,000-point course is worth 20%. The Final worth buttons set 10% to 30%, the range the examples here use, but type whatever your syllabus says. Some courses put more on the final, and some don’t have one.
The weight decides how far one exam can move you. Start at an 85 and score a 70 on the final. At 10%, you finish with 85 × 0.9 + 70 × 0.1 = 83.5, a B. At 30%, it’s 85 × 0.7 + 70 × 0.3 = 80.5, a B-. For a high school semester exam that’s averaged with two quarter grades, use the semester grade calculator instead.
What do I need on the final to pass?
Passing usually means a D: 65 on the scale this site uses, 60 on a straight 10-point scale. Tap Pass (65) or Pass (60) to set the goal. Here’s what the final has to be from two starting points:
| Current grade | Final weight | Need for 65 | Need for 60 |
|---|---|---|---|
| 70 | 10% | 20 | any score |
| 70 | 20% | 45 | 20 |
| 70 | 30% | 53.3 | 36.7 |
| 62 | 10% | 92 | 42 |
| 62 | 20% | 77 | 52 |
| 62 | 30% | 72 | 55.3 |
Look at the rows for a 62. When you’re below the line, a heavier final makes passing easier, because more of the grade is still open: a 72 does it on a 30% final, while a 10% final asks for a 92. Above the line it works the other way, and a heavy final is the one to prepare for.
Before you trust the number
- Check that your current grade is up to date. Missing assignments that are still to be graded can change it.
- Check how your teacher rounds. Some round an 89.5 up to an A-, some do not. Aim a little above the cutoff. Check, too, if your teacher curves the final, since a curve changes the score you need.
- Check for a replacement policy. Some classes let the final replace your lowest test score, which changes the math.
Not sure what your current grade is? Work it out from your category weights with the grade calculator first. Once you know your final grades, see what they do to your average with the GPA calculator, or check where you stand overall in what counts as a good GPA.