Final grade calculator
What score do you need on your final exam to land on the grade you want? Enter your current grade and the final's weight below — the answer updates as you type, with no server round-trip.
What do I need on my final?
Your grade going into the final, how much the final is worth, and the overall grade you're aiming for.
The formula
Let current be your grade going into the final, w be the final's weight as a fraction of the whole grade (a 20% final is w = 0.2), and desired be the overall grade you want. Everything except the final already contributes current at combined weight (1 − w), so:
desired = current × (1 − w) + required × w
Solved for the one unknown, required:
required = (desired − current × (1 − w)) / w
Worked example
Current grade 88%, final worth 20%, target 90% overall:
required = (90 − 88 × 0.8) / 0.2 = (90 − 70.4) / 0.2 = 98%
You'd need a 98% on the final to bring an 88% up to a 90% overall, when the final is worth a fifth of the grade.
Required score to reach 90% overall, by weight and current grade
A quick-reference table for the most commonly asked version of this question — hitting a 90% overall. Rows are your current grade; columns are how much the final is worth. Anything over 100% is not achievable — no score on that final can close the gap.
| Current grade | Final worth 10% | Final worth 20% | Final worth 30% | Final worth 40% |
|---|---|---|---|---|
| 70% | 270.0% — not achievable | 170.0% — not achievable | 136.7% — not achievable | 120.0% — not achievable |
| 75% | 225.0% — not achievable | 150.0% — not achievable | 125.0% — not achievable | 112.5% — not achievable |
| 80% | 180.0% — not achievable | 130.0% — not achievable | 113.3% — not achievable | 105.0% — not achievable |
| 85% | 135.0% — not achievable | 110.0% — not achievable | 101.7% — not achievable | 97.5% |
| 90% | 90.0% | 90.0% | 90.0% | 90.0% |
| 95% | 45.0% | 70.0% | 78.3% | 82.5% |
Notice the pattern down the 90%-current row: it's always exactly 90%, whatever the final is worth — if you're already sitting at your target, the final can't move you off it in either direction, so it needs to match it exactly. Notice too how much a heavier final helps at 85% current: at only 10% weight, 85% needs an impossible 135%; at 40% weight, the same 85% only needs 97.5%. Use the calculator above for your exact numbers — this table only covers whole numbers and a 90% target.
Two more worked examples
Already secured. Current grade 95%, final worth only 10%, target 80%:
required = (80 − 95 × 0.9) / 0.1 = (80 − 85.5) / 0.1 = −55%
A negative required score means the target is already locked in.
Not achievable. Current grade 70%, final worth only 10%, target 90%:
required = (90 − 70 × 0.9) / 0.1 = (90 − 63) / 0.1 = 270%
270% is impossible on any exam — the final's weight is too small to close that gap by itself.
Frequently asked questions
What information do I need before I can use this?
Three numbers: your current grade in the course (as a percentage, before the final), how much the final is worth toward the total grade (also a percentage), and the overall grade you're trying to reach. Your instructor's syllabus is the source for the first two; the third is whatever grade you're aiming for.
Why does a low-weight final make catching up so hard?
Because the final can only move the grade by, at most, its own weight. If the final is worth 10% and you need to gain 20 percentage points overall, even a perfect 100% on the final only contributes 10 points at full weight — it is mathematically incapable of closing a 20-point gap by itself. The lower the final's weight, the steeper the current grade has to already be for a target to stay reachable, which is exactly what the reference table above shows.
What if the number comes out negative?
A negative or zero required score means your target is already secured by your current grade alone, regardless of what you score on the final. It is not an error — it is the formula telling you that the final cannot pull your overall grade below the target, only at or above it.
Can I use this before the final is even scheduled?
Yes. All it needs is your current grade and the final's announced weight, both of which are usually known from day one of the course via the syllabus. You don't need the final's content or format to know what score would satisfy your target.
Does this work for a cumulative final worth a different amount in different courses?
Yes — the weight field is just a percentage of the overall grade, so it applies the same way whether the final is worth 10% in one class or 50% in another. Just use the weight your specific course syllabus states.