Grades
What grade do I need on my final exam?
One formula, and an honest account of when the number it gives you is out of reach.
There is one formula, and it takes about ten seconds once you have three numbers: your current grade, the weight of the final, and the grade you want overall.
needed = ( target − current × (1 − w) ) ÷ w
where w is the final's weight as a decimal — 30% is 0.30
Worked through
You have 78% going into the final. The final is worth 30% of the module. You want 80% overall.
needed = ( 80 − 78 × 0.70 ) ÷ 0.30
needed = ( 80 − 54.6 ) ÷ 0.30
needed = 25.4 ÷ 0.30 = 84.7%
So you need roughly 85% on the final to finish on 80% overall.
Notice how much leverage the weight carries. On the same numbers with a final worth 50%, you would need only 82%. With a final worth 15%, you would need 91.3% — because there is less room left to move the average.
A heavily weighted final is not automatically bad news. It cuts both ways: it can rescue a poor term as easily as it can sink a good one. It is a low-weighted final, late in a term that went badly, that leaves you with nothing to work with.
When the answer is impossible
The formula will happily return 112%. That is real information, not an error.
If the number comes back above 100, the grade you were aiming for is arithmetically out of reach, no matter how well you do. It is far better to know that a fortnight before the exam than to find out afterwards.
What to do with it:
- Recalculate for the next grade down. The boundary you can still reach is the one worth working towards.
- Check for anything that changes the arithmetic. A dropped-lowest-score policy, an optional resit, extra credit, a coursework mark not yet returned.
- Check whether the final has its own pass requirement. Some modules require a minimum on the exam regardless of the overall average, which the formula above does not know about.
The reverse is worth checking too. If the number comes back at 31%, you have already secured the grade you were worried about, and your revision time is better spent on the module where it is genuinely in play.
Weighted categories, not a single final
Most modules are not one final and one running average. They are categories with their own weights:
| Component | Weight | Your score |
|---|---|---|
| Coursework | 40% | 82% |
| Mid-term | 20% | 74% |
| Participation | 10% | 95% |
| Final exam | 30% | ? |
Multiply each score by its weight and add them up:
(82 × 0.40) + (74 × 0.20) + (95 × 0.10) = 32.8 + 14.8 + 9.5 = 57.1 points
For 80% overall, the final must supply80 − 57.1 = 22.9 points, from a component worth 30
22.9 ÷ 0.30 = 76.3%
Which is a good deal more encouraging than the first example, and shows why it is worth doing this with your real category weights rather than a single “current grade” figure.
Three things that quietly change the answer
Rounding. A module that rounds to the nearest whole percent means 79.5 becomes 80. A module that truncates means 79.9 is still 79. Over a boundary, that is a grade.
Dropped scores. “Lowest quiz dropped” changes the denominator, not just the numerator, and usually helps you more than expected.
Curving. If your marks are curved to a distribution, none of this arithmetic is final until the curve is applied. Ask before you plan around a target.
Do it without the arithmetic
Our final grade calculator does this for every letter grade at once, so instead of one answer you get the full picture — what you need for an A, a B, a C — and it tells you plainly when a target has become unreachable rather than returning a number above 100 and leaving you to interpret it.
If you are working out where a module leaves your overall average, the GPA calculator handles credit weighting and shows the quality points per course, so you can see which modules are actually moving your average and which are noise.