Required final score = (target grade − current grade × (1 − final weight)) ÷ final weight, using the final's weight as a decimal share of the course grade. A student at 88% needing a B (83%) on a final worth 25% needs only 63% — because the current grade already carries most of the course.
The formula, explained
A course grade is a weighted average: final course grade = current grade × (1 − final weight) + final exam score × final weight. Solving that equation for the unknown final exam score gives the required-score formula.
The current grade should reflect everything graded before the final — the weighted average of all other categories, not a raw point total, unless the course truly is 100% points-based.
Worked example
A student has a 78% average going into a final worth 30% of the grade and wants to reach an 80% overall.
| Value | Amount |
|---|---|
| Current grade | 78% |
| Final exam weight | 30% |
| Target grade | 80% |
| Required final score | (80 − 78 × 0.7) ÷ 0.3 = 84.7% |
When the required score is impossible
If the formula returns a number above 100%, the target is not reachable through the final alone. This happens when the current grade is well below the target and the final's weight is too small to close the gap even with a perfect score. Options at that point include extra credit, grade replacement policies, or accepting a lower final grade.
When the final is curved
Calculate the required raw score first using the uncurved formula, then apply any announced curve afterward. If an instructor adds points after grading, the effective raw score needed is lower than the calculation shows — but do not assume a curve in advance unless it is part of the stated policy.
Grade Calculator Editorial Team
We create plain-language grading tools and educational guides, check every worked example against the underlying formula, and note where school or instructor policies can change the result.