How the final grade calculator works
Your course grade is a weighted average of everything you have done so far and the final exam. If the final is worth w (as a decimal), then everything before it is worth 1 - w. Setting that average equal to the grade you want and solving for the final gives:
needed = (target - current x (1 - w)) / w
where current is your grade before the final, target is the grade you want to finish with, and w is the final's weight as a decimal (40% is 0.4).
Worked example
Say you have an 85% going into a final worth 40% of the course and want to end with a 90%. The 85% covers the other 60% of your grade:
needed = (90 - 85 x 0.6) / 0.4
= (90 - 51) / 0.4
= 39 / 0.4
= 97.5%You would need a 97.5% on the final. Check it: 85 x 0.6 + 97.5 x 0.4 = 51 + 39 = 90. A 90 is technically possible but demanding; the table below shows what more realistic targets require.
Grade needed for each target (current 85%, final worth 40%)
| Target grade | Needed on the final |
|---|---|
| 60% | 22.5% |
| 65% | 35.0% |
| 70% | 47.5% |
| 75% | 60.0% |
| 80% | 72.5% |
| 85% | 85.0% |
| 90% | 97.5% |
| 95% | 110.0% |
Why the final's weight matters so much
A heavier final gives you more room to move in either direction. With a 20% final, the 85% student needs a 110% to hit 90, which is impossible, but is also guaranteed a B- or better with just a 65% on the exam. With a 50% final, a 95% would do it, and a 75% would still hold an 80. The weight divides the gap between where you are and where you want to be, so small weights amplify the score you need.
Finding your current grade and the final's weight
Most learning management systems show a running percentage that already excludes ungraded items; that is the number to use. The final's weight is in the syllabus. If the syllabus lists points instead of percentages (for example, final = 200 of 1,000 total points), the weight is 200 / 1,000 = 20%. If you have categories with different weights, compute your current standing first with the grade calculator, then bring the result here.
Letter grade cutoffs
Targets are usually letter cutoffs. On the common scale, 90 is an A-, 80 a B-, 70 a C-, and 60 a D-. Plus grades start at 87, 77, and 67; straight A, B, C start at 93, 83, and 73. Aim one point above the cutoff to leave a margin for rounding differences in your instructor's gradebook.