My final is worth 20% — what score do I need?
A fifth is the commonest weight there is, and it produces a simple rule: every point you want to gain costs five points on the exam. From 77% aiming at 80, that means a 92. Four fifths of your grade is already decided, and the table below shows what the last fifth can do.
Common plus/minus convention; many schools use straight letters or different cut points.
You need 92% on the final.
That is within reach — the final is worth 20% of your grade.
🔢 Show the math
- Work graded so far covers 80% of the course; 20% is still to come.
- Points already banked: 77% × 80% = 61.6 points of the 100 available.
- To finish at 80% you still need 18.4 points from the remaining 20%.
- 18.4 ÷ 20 × 100 = 92% on what is left.
What you need, at every current grade
With a final worth 20% of your course grade and a B- (80%) as the goal, this is the score you need on the final from each starting point:
| Current grade | You need on the final | Reachable? |
|---|---|---|
| 88% | 48.0% | Yes |
| 83% | 68.0% | Yes |
| 80% | 80.0% | Yes |
| 77% | 92.0% | Yes |
| 72% | 112.0% | Not with this final alone |
| 66% | 136.0% | Not with this final alone |
Grading scales vary by institution — your school's own table and syllabus govern. Conversions shown here follow common published conventions.
Frequently asked questions
What is the most a 20% final can change?
Twenty points, between a perfect paper and a blank one, and realistically about six. From 77% your possible finishes run from 61.6 to 81.6. That range decides borderline letters and nothing else, so a target more than four points above your current grade is usually already gone at this weight.
Where does the five-to-one ratio come from?
From the weight itself. The exam contributes a fifth of the average, so a point scored on it delivers a fifth of a point to the course. Reverse that and each point of course grade costs five exam points. The same arithmetic gives ten-to-one at 10% weight and two-to-one at 50%.
How should I split revision between a 20% final and a heavier one?
By where the marks move, not by which exam frightens you. An hour spent on a 40% paper shifts twice as much course grade as an hour on this one. The exception is a boundary: if a single point decides your letter here and nothing is at stake elsewhere, this exam wins the hour.
Is anything else still in play besides the exam?
Often, and it is worth checking before the exam becomes your only lever. Outstanding submissions, a resubmission window, a dropped-lowest rule, or unclaimed participation credit all change your current grade directly — and at this weight, a point added there is worth five points of exam performance.
Other targets
The free study kit: schedule template, exam-day checklist, grade tracker
One email when the numbers change. Double opt-in, no spam, unsubscribe anytime.