I Have a 77 in the Class — What Do I Need on the Final?
Going into the final with a 77%: if the final is worth the typical 20%, you need more than a perfect score (an A isn't reachable) and 92% for a B. Every common weight is below — or set your exact numbers in the calculator.
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What you need at every final-exam weight
| Final worth | For A | For B | For C | For Pass (D) |
|---|---|---|---|---|
| 10% | Not possible | Not possible | 7% | Locked in ✓ |
| 15% | Not possible | 97% | 30.3% | Locked in ✓ |
| 20% | Not possible | 92% | 42% | Locked in ✓ |
| 25% | Not possible | 89% | 49% | 9% |
| 30% | Not possible | 87% | 53.7% | 20.3% |
| 40% | Not possible | 84.5% | 59.5% | 34.5% |
| 50% | Not possible | 83% | 63% | 43% |
Reading this table
"Locked in" means even a zero on the final keeps that grade. "Not possible" means a perfect final still wouldn't get you there — with a 77% and a heavily weighted final, your ceiling is 88.5% (50% weight) to 79.3% (10% weight). The math: needed = (target − current × (1 − weight)) ÷ weight.
Worth knowing
Ask about rounding before finals week
An 89.5 is an A- in some classes and a B+ in others. Professors have wildly different rounding policies, and the polite time to ask is mid-semester, not the night grades post.
The final isn't all-or-nothing
Because finals are usually worth 20–40%, your semester of work is protecting you more than you think. Run the numbers: the score you actually need is often lower — sometimes dramatically lower — than the panic estimate.
Common questions
What's the difference between weighted and unweighted averages?
An unweighted average treats every score equally: add them up, divide by the count. A weighted average multiplies each category by its share of the grade first — homework 20%, midterms 40%, final 40% — which is how most courses actually work. If your syllabus lists category percentages, you need the weighted version.
How are letter grades calculated from percentages?
Most US schools map percentages to letters in 10-point bands: 90–100 is an A range, 80–89 a B range, 70–79 a C range, 60–69 a D range, and below 60 an F. Plus/minus splits each band roughly in thirds (e.g. 90–92 = A-, 93–96 = A, 97+ = A+). Individual schools and professors can and do vary the cutoffs.