What this calculator answers
One question: what is the lowest score on the final exam that still gets you the course grade you want. You give it three things — where you stand now, where you want to finish, and how much of the grade the exam carries — and it works backwards.
It also tells you when the answer is not a score at all. Sometimes the target is already locked in and a zero would still clear it. Sometimes it is gone and a perfect paper falls short. Both are real outcomes, and a calculator that prints a number in those cases is printing a number that means nothing.
How to use it
- Current grade. The percentage your gradebook shows for graded work, with the final exam not counted. If the final is in there as a zero, take it out first — otherwise your current grade is too low and the score you need comes out too high.
- Target grade. What you want to finish the course on. Type a percentage, or pick a letter and the box fills with the bottom of that band, which is what wanting that letter actually means.
- Final exam weight. Its share of the course grade, off the syllabus. Not the marks the paper is out of.
- Read the answer, and the arithmetic under it. The score you need, the letter it corresponds to, how much of the course you have banked, and how much weight is still live.
If other work is still outstanding besides the exam, open Other work left, and rounding and add it. That panel also holds the rounding policy, which moves the answer near a cutoff.
The arithmetic, one step at a time
Worth walking through once, because the shortcut most people reach for is wrong. Take a 87% current grade, a 90% target, and a final worth 30% of the course:
- The graded part of the course is 70% of it — everything except the exam.
- Your 87% on that 70% is 87 × 0.70 = 60.90% of the course, banked.
- You need 90.0% in total, so 90.0% − 60.90% = 29.10% still has to be earned.
- That has to come out of the exam's 30%, so 29.10% ÷ 0.30 = 97.00%.
Needed = (target − current × (100 − weight) ÷ 100) ÷ weight × 100
Now the shortcut: the gap between 87% and 90% is 3%, and dividing that by 30% gives 10.00%, which you might then add to 87. It is a tempting piece of arithmetic and it is not right. Raising your course grade by three points means finding three points of the whole course inside the exam's 30% — and it also means the exam has to clear your target outright, not merely match your current grade. The real answer is 97.00%, which is a good deal less comfortable.
Three worked examples
Each one computed by the function the calculator runs, at the same rounding:
| Current grade | Exam weight | Target | Banked | Needed on the final |
|---|---|---|---|---|
| 87% | 30% | 90% | 60.90% | 97.00% |
| 78% | 40% | 80% | 46.80% | 83.00% |
| 92% | 25% | 90% | 69.00% | 84.00% |
The third row is the interesting one. Sitting on 92% with a 90% target, you can drop to 84.00% on the final and still finish where you wanted — because the 75% already graded is carrying you. The second row shows the same effect from underneath: a 78% needs only 83.00% for a 80%, because the target is close and the exam is heavy enough to move you there.
When the answer is not a number
Two outcomes that look like errors and are not:
- Already secured. A 98% going into a final worth 10%, aiming at 85%, finishes at 88.20% even with a zero on the exam. The answer is 0.0% — a real answer, not a missing one.
- Out of reach. An 85% going into a final worth 25% cannot reach 90%: a perfect paper finishes the course at 88.75%. The calculator says that instead of printing a figure above 100.
If you are in the second case, the exam is not where the answer is. Outstanding work you can still submit, extra credit, a curve, or a policy that lets the final replace a lower score are the things that move a current grade; the exam only ever moves its own share.
Other work left over, and why it matters this much
The three fields assume the exam is all that is left. Often it is not — a project, a last homework set, a participation grade. Add them in the advanced panel and the answer changes, sometimes from impossible to comfortable:
| What is left | Live weight | Needed across it |
|---|---|---|
| Final exam only | 25% | Out of reach |
| Final exam and a group project | 35% | 99.29% |
Same student, same 85%, same 90% target. The first row says the grade is gone. The second says it needs 99.29% across both pieces — hard, but a different conversation entirely. If there is outstanding work you have not counted, you are reading the wrong row.
One rule when you use the panel: enter each outstanding item once, with its own weight, and let the total be worked out. Adding the project's weight onto the exam's field and also listing the project is the way to double-count it.
Rounding, and the tenth of a point that costs a letter
If your teacher rounds, your target is not quite your target. A 90% goal under whole-percent rounding is really 89.5%, because 89.5% rounds up to it. Same case, three policies:
| Policy | Target becomes | Needed on the final |
|---|---|---|
| The course grade is used exactly as calculated. A target of 90 means 90.000. | 90.00% | 94.67% |
| The course grade is rounded to the nearest whole mark, so 89.5 is recorded as 90. | 89.50% | 93.00% |
| The course grade is rounded to one decimal place, so 89.95 is recorded as 90.0. | 89.95% | 94.50% |
The spread across those three rows is small and it is exactly the size that decides a letter. Set the policy to what your syllabus states and nothing else: assuming rounding that is not there is how a grade gets missed by a tenth of a point, and assuming none when there is some makes you study for marks you did not need.
What each score on the final actually gets you
The question from the other end, and often the more useful one. Same 87% current grade and 30% exam:
| Score on the final | Course finishes at | Letter |
|---|---|---|
| 60% | 78.90% | C+ |
| 70% | 81.90% | B- |
| 80% | 84.90% | B |
| 90% | 87.90% | B+ |
| 100% | 90.90% | A- |
The gap between the top and bottom rows is the whole influence the exam has: 90.90% at best against 78.90% at worst. That range is the honest measure of how much this exam matters, and the calculator shows it whether or not you have entered a target.
How much the weight changes the difficulty
A heavy final is easier to use and more dangerous to fail. The same 87% chasing the same 90%, with the exam worth different amounts:
| Exam weight | Needed on the final |
|---|---|
| 10% | Out of reach |
| 20% | Out of reach |
| 30% | 97.00% |
| 40% | 94.50% |
| 50% | 93.00% |
Read it top to bottom: when the exam is worth little, closing even a small gap takes a score you may not be able to get, and at the extreme the gap cannot be closed at all. When it is worth a lot, the same gap closes with a much more ordinary paper. This is why "the final is worth half the grade" is not automatically bad news for someone behind — and why it is very bad news for someone comfortably ahead.
Why your required score might look wrong
If the number surprises you, work down this list before believing it. Five of the six are input problems, and all six are settled by your syllabus rather than by any calculator:
| Cause | What is happening |
|---|---|
| The final is already in your current grade | Many gradebooks show an unsat exam as a zero. That drags your current grade down, and entering it here asks the calculator to make up ground you have not actually lost. Remove the exam and recompute before entering the figure. |
| The weight is the exam's point total | A 200-mark final in a 1,000-point course is 20% of the grade, not 200. Entering the point total makes the required score look far kinder than it is. The syllabus states the share. |
| The current grade is a category average | An 88% in Tests is not an 88% in the course. Weight your categories together first — or work the grade out from your assignments and bring that figure here. |
| A dropped score has not been applied | If the lowest quiz is dropped at the end of term, your gradebook may still be counting it. Recalculate without it; your current grade goes up and the required score comes down. |
| Rounding, extra credit or a curve | All three change your current grade rather than the arithmetic here. Update the current grade to what it will actually be, then read the answer. |
| The target is a letter boundary, not a number | "I need a B" is a cutoff, and cutoffs differ by school. Setting the target from the letter picker uses the bottom of the band on the scale you have selected, which is the figure that sentence actually means. |
Using it to plan rather than to panic
- Check the target before you commit to it. Compare the required score to what you have been scoring on tests in this course. If it is well above, that is information, not a challenge.
- Look for weight you have not counted. Outstanding work is the cheapest thing on the page. A make-up assignment often moves the required score further than a week of revision would.
- Try the target one letter down. Knowing what secures a B while you chase an A− tells you where the floor is, which is worth knowing before exam week rather than after.
- Work out the score that holds your current grade. Set the target equal to your current grade and the answer is the score that leaves you exactly where you are.
Related calculators
The Grade Calculator works your current grade out from individual assignments, which is where the figure at the top of this page should come from. The Weighted Grade Calculator does the same across syllabus categories, with points-mode entry. For the transcript rather than one course, the College GPA Calculator weights by credit hour, and the guide to calculating grades covers the arithmetic by hand.