What Do I Need on My Final Exam? How to Calculate It

The Formula: What You Need on Your Final

Required Final Score = (Target Grade − Current Grade × (1 − Final Weight)) ÷ Final Weight

All values are in decimal form (percentages ÷ 100).

Worked Examples

Example 1: On the edge. Current grade: 78%. Target grade: 80%. Final exam weight: 30%.

Required = (0.80 − 0.78 × 0.70) ÷ 0.30 = (0.80 − 0.546) ÷ 0.30 = 0.254 ÷ 0.30 = 84.7% needed on the final.

Example 2: Safely ahead. Current grade: 92%. Target grade: 90%. Final exam weight: 25%.

Required = (0.90 − 0.92 × 0.75) ÷ 0.25 = (0.90 − 0.69) ÷ 0.25 = 0.21 ÷ 0.25 = 84% needed. Even with an 84% on the final, you'd still get an A-.

Example 3: In trouble. Current grade: 55%. Target grade: 70% (C). Final exam weight: 30%.

Required = (0.70 − 0.55 × 0.70) ÷ 0.30 = (0.70 − 0.385) ÷ 0.30 = 0.315 ÷ 0.30 = 105% — mathematically impossible.

What If You Need Over 100%?

If the formula returns over 100%, you cannot reach your target grade through the final exam alone. Your options: lower your target grade and recalculate, ask your professor if there's extra credit, or speak with your academic advisor about incomplete grades if extenuating circumstances apply.

Accounting for Curves

If your professor grades on a curve, the formula still works — just use your post-curve current grade and the post-curve target grade. Many professors announce curves only at the end of semester, so calculate conservatively with your raw scores and treat any curve as a bonus.

Frequently Asked Questions

My final is only worth 20% — does it really matter?

Less than finals worth 30-40%, but still significant. With a 20% final, a 100% on the final only raises your grade by 20 × (1 − current percentage). If you're at an 88% and need 90%, you'd need: (0.90 − 0.88 × 0.80) ÷ 0.20 = (0.90 − 0.704) ÷ 0.20 = 98% on the final. Even a small target jump can require a very high score when the final is weighted low.