How to Calculate Your Final Grade (and What You Need on the Exam)
The formula, three worked examples, and what to do when the score you need is above 100%.
To find the score you need on a final exam, use this formula: score needed = (target grade − current grade × (1 − w)) ÷ w, where w is the weight of the final exam as a decimal. For example, with 88% now, a final worth 30% and a 90% target, you need (90 − 88 × 0.70) ÷ 0.30 = 94.67%. The final grade calculator does this for you in a second, and this guide shows how it works.
If you are new to grade arithmetic, read our guide on how to calculate grades first. For the weighting ideas behind the formula, see weighted grades explained.
- The final is one more weighted category, so your course grade = current × (1 − w) + final × w.
- Rearranged, the score needed is (target − current × (1 − w)) ÷ w.
- The heavier the final, the more it can change your grade, in either direction.
- If the answer is above 100%, the target is out of reach without extra credit or a change of target.
The idea behind the formula
Your course grade is a weighted average of two parts: the work already graded, and the final exam. If the final is worth w of the course (30% is w = 0.30), then the graded work is worth 1 − w (0.70). So:
course grade = current × (1 − w) + final × w
You know the current grade, the weight and your target. You want the final score, so you solve for it: subtract current × (1 − w) from the target, then divide by w. That gives the formula in the lead.
Step-by-step method
- Write down your current grade as a percentage, based only on the work graded so far.
- Find the weight of the final in your syllabus, and write it as a decimal (25% = 0.25).
- Choose your target for the course, for example 90% for an A on the 10-point scale.
- Work out current × (1 − w). This is the part of the course grade you have already banked.
- Subtract it from the target, then divide the result by w.
The answer is the percentage you need on the final. Anything above that gets you past your target, and anything below leaves you short.
Three worked examples
Example 1: aiming for an A
Current grade 88%, final worth 30%, target 90%. The banked part is 88 × 0.70 = 61.60. Then (90 − 61.60) ÷ 0.30 = 28.40 ÷ 0.30 = 94.67%. Check it: 61.60 + 94.67 × 0.30 = 90.00.
Example 2: a lighter final
Current grade 76.5%, final worth 25%, target 80%. The banked part is 76.5 × 0.75 = 57.375. Then (80 − 57.375) ÷ 0.25 = 22.625 ÷ 0.25 = 90.5%. A lighter final means you must score higher to move the same distance.
Example 3: just passing
Current grade 72%, final worth 35%, and you only need 60% to pass. The banked part is 72 × 0.65 = 46.80. Then (60 − 46.80) ÷ 0.35 = 13.20 ÷ 0.35 = 37.71%. Do not stop revising, but this is a very different task from Example 1.
For a quick feel of how the target changes the answer, here is the same student as Example 1 (88% now, 30% final) with different targets:
| Target | Needed on final |
|---|---|
| 80% | 61.33% |
| 85% | 78.00% |
| 90% | 94.67% |
Finding your current grade first
The formula needs a current grade, and your gradebook may show categories instead of one number. Combine them first with the weighted grade calculator. For instance, suppose Homework is 20% with a score of 90%, Quizzes 20% with 85% and Tests 30% with 80%, and the final is the remaining 30%. The banked part is 0.20 × 90 + 0.20 × 85 + 0.30 × 80 = 18 + 17 + 24 = 59 points.
You can use that 59 directly in the formula. To finish on 85%, you need (85 − 59) ÷ 0.30 = 26 ÷ 0.30 = 86.67% on the final. Your current grade as a percentage of the graded work is 59 ÷ 0.70 = 84.29%, and using it gives the same answer.
If the answer is over 100%
Sometimes the maths says the target is impossible. A student with 70% and a final worth 20% who wants 90% needs (90 − 56) ÷ 0.20 = 170%. Even a perfect final gives 70 × 0.80 + 100 × 0.20 = 76%, so a 90% finish cannot happen.
When that happens you have a few honest options:
- Lower the target. Run the formula for a lower grade you can reach, such as 76% if you score full marks.
- Look for extra credit. If your teacher offers it, see how extra credit can lift the final result.
- Ask about retakes or corrections. Some courses allow grades to be improved before the final.
- Check the inputs. A wrong weight or an out-of-date current grade can make a target look worse than it is.
Rounding the result
The formula often gives a decimal such as 94.67%. In practice, round the number you need up, to 95%, so that you stay safely above the line. Then check how your teacher rounds the course grade itself, because a borderline result can fall either way. Our guide to grade rounding explains the common policies.
Find your target score
Enter your current grade, the final’s weight and your goal.
Open the final grade calculatorFrequently asked questions
How do I calculate what I need on my final?
Use (target − current × (1 − w)) ÷ w, where w is the final’s weight as a decimal. With 88% now, a 30% final and a 90% target, you need 94.67%.
What is the final grade formula?
Course grade = current × (1 − w) + final × w. Solving for the final score gives (target − current × (1 − w)) ÷ w.
What if I need more than 100% on the final?
The target cannot be reached with the final alone. Lower the target, ask about extra credit or retakes, or check that your weight and current grade are correct.
How much is the final worth?
It depends on the course. Your syllabus will say, and common weights are between 20% and 40%.
Does the formula work with category weights?
Yes. Combine your categories into a current grade first, or add up the banked points directly, then apply the same formula with the final’s weight.
- See all the weighted-average maths in weighted grades explained.
- Planning ahead? Read how extra credit affects your grade.