What Do I Need on My Final? The Exam Grade Formula, Worked Out
It is the most googled grade question of every exam season: what do I need on the final? The answer comes from one short formula built on your current grade, your target grade, and how much the final is worth.
The formula
Your end-of-course grade is a weighted average of two pieces: everything before the final, and the final itself. If the final is worth w (as a decimal), your current grade is C, and your target is T, then the score you need on the final is: Needed = (T - C x (1 - w)) / w. That is the whole trick.
Worked example 1: a realistic target
You have an 82 average and the final counts for 30% of the grade. You want to finish with at least 85. Plug in: Needed = (85 - 82 x 0.7) / 0.3 = (85 - 57.4) / 0.3 = 27.6 / 0.3 = 92. You need a 92 on the final. Tough but doable.
Worked example 2: how much can you coast?
The same formula tells you the floor. Current grade 91, final worth 20%, and you want to keep at least an A at 90: Needed = (90 - 91 x 0.8) / 0.2 = (90 - 72.8) / 0.2 = 17.2 / 0.2 = 86. You can score as low as an 86 on the final and still keep your A. Knowing your floor is just as useful as knowing your stretch target.
When the target is impossible (or already locked in)
If the formula spits out a number above the maximum possible score, the target is mathematically out of reach. Example: current grade 70, final worth 20%, target 90 gives Needed = (90 - 70 x 0.8) / 0.2 = (90 - 56) / 0.2 = 170. No final exam pays out 170%, so it is time to adjust the target or talk to the teacher about extra credit. The reverse also happens: if the result is negative or below the minimum score, the target is already guaranteed, and the final cannot take it away from you.
The same idea on 1-6 and other scales
The formula is scale-independent, with one twist: on inverted scales like Germany's 1-6, where lower is better, aiming for a better grade means solving for a lower number. If your current German average is 2.6, the final counts 50%, and you want a 2.0 overall, you need (2.0 - 2.6 x 0.5) / 0.5 = 1.4 on the exam. The arithmetic is identical, only the direction of good flips.
Or skip the algebra entirely
The exam calculator in GradeBuddy does this computation for you: pick the subject, set the final's weight and your target, and it shows exactly what score you need, in your school's own grading system. It also plays nicely with weighted categories, which the guide on weighted grade averages covers in detail.
Common questions
- How do I calculate what I need on my final exam?
- Use: needed score = (target grade - current grade x (1 - final weight)) / final weight, with the weight as a decimal. Example: 78 current, final worth 25%, target 80: (80 - 78 x 0.75) / 0.25 = 86.
- What grade do I need on a final worth 20 percent?
- Multiply your current grade by 0.8, subtract that from your target, and divide by 0.2. With an 85 average and a 90 target: (90 - 68) / 0.2 = 110, which is impossible, so a 90 is out of reach in that scenario.
- Can I still pass if I fail the final?
- Sometimes. Compute your worst case: current grade x (1 - final weight) + minimum final score x final weight. If that lands at or above the passing line, you pass even with a zero. Some courses have must-pass finals, so check the syllabus.
- What if the score I need is over 100?
- Then the target is mathematically impossible with the final alone. Lower the target, ask about extra credit or retakes, or focus on the best grade still achievable, which the same formula can tell you by testing targets.