Calculate Final Grade (Weights)

A comprehensive guide on how to calculate your final grade using weighted percentages and your current scores.

The Weighted Final Grade Formula

Most classes calculate your final grade using this formula: Final Grade = (Current Grade × Current Weight) + (Final Exam Score × Final Exam Weight), where the current weight is simply 100% minus the final exam's weight.

A Worked Example

Say your current grade going into finals is 85%, and your final exam is worth 20% of your total grade (meaning everything else is worth the remaining 80%). If you score a 90% on the final: (85 × 0.80) + (90 × 0.20) = 68 + 18 = 86% final grade.

Working Backwards: What Score Do You Need?

Often the more useful question isn't "what's my grade if I get X on the final" but "what do I need to get on the final to reach a target grade." Rearranging the formula: Required Score = (Target Grade − (Current Grade × Current Weight)) ÷ Final Exam Weight.

Using the same numbers but targeting a 90% final grade: (90 − (85 × 0.80)) ÷ 0.20 = (90 − 68) ÷ 0.20 = 22 ÷ 0.20 = 110% — meaning it's mathematically impossible without extra credit, since you can't score above 100% on a standard exam.

Why the Weight Percentage Matters So Much

The same 90% final exam score can mean wildly different things depending on how much it's worth. At a 10% weight, a poor final barely moves your grade. At a 50% weight (common in some college courses), a single bad exam can undo an entire semester of strong work. Always confirm the exact weight from your syllabus before assuming anything about your final grade.

Skip the Manual Algebra

Rearranging this formula by hand is where most calculation mistakes happen, especially under finals-week stress. Our Final Grade Calculator does this instantly — just enter your current grade, the final's weight, and your target grade to see exactly what score you need.