What Do I Need on My Final? The Arithmetic, and the Four Ways It Misleads

The question has an exact answer, and it takes one line of algebra. Take the grade you want, subtract the weighted points you have already banked, and divide by the weight of everything still ungraded:

needed = (target − points already earned) ÷ remaining weight × 100

Almost nobody gets that wrong. What goes wrong is everything upstream of it — the numbers you feed in. Three of the four mistakes below produce a confident, plausible, wrong answer with nothing on screen to suggest anything is off. This page is about those, not about the division.

The worked example

One course, four components, one of them ungraded. This is the whole calculation, and the rest of the page refers back to it.

Each component contributes its score times its weight: 88 × 20% is 17.6 points out of a possible 20. Add those up and you have banked 50.35 points of the 60 that have been graded so far. That single figure decides everything below.

Set a target, and the formula answers immediately:

• For an 80: (80 − 50.35) ÷ 40 × 100 = 74.1 on the final.
• For a 90: (90 − 50.35) ÷ 40 × 100 = 99.1 on the final.
• For a 93: (93 − 50.35) ÷ 40 × 100 = 106.6 — more than the exam is worth.

1. The running total in your gradebook is not your course grade

Open the course right now and it will most likely say 83.9%. That is 50.35 divided by the 60 points of weight that have actually been graded. It is a correct number and it is the answer to a real question — how have I done on the work handed back so far — but it is not the question you are asking.

Canvas leaves ungraded work out of the total entirely. In the University of Wisconsin–Madison's description of the behaviour, a blank item will not be included in the calculation, and the assignment counts neither for nor against their score appearing as if it has been Excused. Your instructor can switch their own view to treat blanks as zeros; yours does not change.

So the number on your screen is a weighted average of the good part of the term. It will move on its own as work is marked, without you doing anything. And the distance between it and your actual position can be large: 83.9 looks like a comfortable B, and an A at 90 needs a 99.1 on the final. Nothing in the gradebook tells you that. The 83.9 is not lying — it is answering a different question, quietly.

2. Anything conditional has to be resolved before it reaches the formula

Syllabus rules that fire on a condition — the lowest quiz is dropped, the midterm is replaced by the final if the final is higher, an exam is curved — are not part of the weighting scheme. They change which number goes in the box, and they have to be settled first.

If the lowest of five quizzes is dropped, average the four that count and enter that as your quiz score. If an exam was curved, enter the curved score. A calculator cannot do this for you without you telling it the rule, and the calculator deliberately applies no rule your syllabus did not state — which is why a conditional rule is your job to collapse into one figure before you start.

The one case worth being careful with is a curve, because the rule is usually not written down anywhere. If you are guessing at what a curve did to a score, you are guessing at the input that decides your answer — the four documented curve methods give different results from the same raw score, and no method is standard.

3. If the weights do not add to 100, do not scale them

Type your syllabus in and you may find it totals 105, or 95. The instinct is to assume a rounding error and normalise. Do not — and note that our tools do not either, which is why the total is shown to you rather than tidied away.

A total that is not 100 is almost always a real signal: a component you have forgotten, a duplicated row, or a participation line added to the course after the syllabus was written. Any of those changes the answer. Scaling silently converts a question you could have asked your instructor into a number you will trust by mistake.

And you are entitled to ask. Penn State's Senate Policy 47-20 requires the basis for grades to be given to students in writing on or before the first class meeting, and any change to that basis to be put in writing too. The University of Toronto goes further and names the weights specifically: evaluation methods and their relative weights have to be disclosed, and once they are known they cannot be changed without the consent of a simple majority of the class. Neither policy governs your course unless you attend those schools — but they establish that a written, stable weighting scheme is a normal expectation rather than a favour, which is the premise every calculation on this site rests on.

4. A needed score over 100 is the end of that target, not the end

The 93 line above came out at 106.6. That is not an error and the calculator will show it rather than clamping it to 100: it means the target is arithmetically out of reach with the work that is left, and it is better to know in week 11 than to find out in week 15.

What it does not mean is that nothing is worth doing. The next question is what target is still reachable, which is the same formula run backwards — a perfect 100 on this final lands the course at 50.35 + 40 = 90.35. So the A− is live and the A is not, and the difference between working hard and working very hard is now a decision you can actually make.

Where this site stops is the letter. An A− begins at 90 in one course and 92 in another, and plenty of schools have no minus grades at all — so the cut-offs are not ours to guess. Read the percentage for the letter you want off your own syllabus and use that as the target. If your school publishes a scale and you want to see what a percentage is worth as a grade point, the scale converter shows four published university scales side by side rather than inventing a fifth.

The short version

The arithmetic is trustworthy and it is not where the risk is. Before you rely on an answer, check three things: that the number you started from is the weighted total of graded work and not your course grade, that every conditional rule has already been turned into a plain score, and that the weights you typed are the ones your syllabus actually states — including their total. Get those right and the division at the top is exact.