Weighted categories, worked through
A syllabus that says homework 20 percent, quizzes 15, midterm 15, projects 20 and final 30 is describing a weighted average, not a plain one. Each category is averaged on its own, that average is multiplied by the weight, and the products are added. A student with 93.75 in homework, 84 in quizzes, 86 on the midterm and 89.5 in projects has banked 18.75 + 12.6 + 12.9 + 17.9, or 62.15 points out of the 70 that have been decided — an average of 88.8 on the graded work, and 62.15 of the 100 points in the course.
The distinction between those last two numbers is where most confusion lives. The 88.8 is the average so far. The 62.15 is what is actually banked toward the final grade. The final exam does not adjust the 88.8; it adds up to 30 more points to the 62.15.
The score needed on the final
Solve the same equation for the unknown. With E points banked, W percent of the grade still outstanding and a target T:
needed = (T − E) × 100 ÷ W
Take a student averaging 88 percent across work worth 70 percent of the grade, with a final worth 30, aiming at 90 overall. Banked points are 88 × 0.70 = 61.6. The final has to supply 90 − 61.6 = 28.4 points from a slot worth 30, so it has to score 28.4 ÷ 0.30 = 94.7 percent. That is the shape of the result almost every time: a target only two points above the current average requires a final nearly seven points above it, because only 30 percent of the grade is doing the moving.
| Final is worth | Needed to move 88 to 90 |
|---|---|
| 20% | 98.0% |
| 30% | 94.7% |
| 40% | 93.0% |
| 50% | 92.0% |
The lighter the final, the harder it works. This is worth checking at the start of a term rather than at the end of one, because it determines how much of the grade is recoverable later and how much has to be protected week by week.
When the answer is that it cannot be done
If the required score comes out above 100, the target is gone, and the useful thing a calculator can do is say so directly instead of printing an impossible number without comment. A student sitting at 62 percent across 70 percent of the grade has banked 43.4 points. An A at 90 would need 46.6 points from a 30-point final, which is 155 percent. No amount of preparation produces that.
What is worth knowing at that point is the actual ceiling — 43.4 plus 30 is 73.4 percent, a C. This page prints the best and worst possible finishing grades whenever any work is outstanding, precisely so the question can be reframed. Knowing that the realistic range is a C to a C-minus changes what the last two weeks are for, and it changes it in a more useful direction than chasing an A that stopped existing in October.
Where this stops matching the gradebook
Several common policies are not modelled here and will pull the real grade away from this one. Dropped lowest scores, where a category discards its worst mark before averaging, mean you should leave that score out of the line. Points-based courses, which total raw points earned over raw points possible rather than weighting categories, are a different calculation entirely — in those, a 200-point final really is worth twice a 100-point midterm regardless of what the syllabus calls them. Curves, extra credit, attendance adjustments and rounding rules at the boundary all sit outside the arithmetic too. Read the syllabus for which system your course uses before trusting any projection, this one included.
Questions people ask
My weights add up to 95, not 100. What happens?
The calculation still runs — everything is divided by the total you entered rather than by an assumed 100 — and a line appears telling you the weights do not sum to 100. That is usually a signal of a missing category rather than an unusual grading scheme, so it is worth going back to the syllabus. Occasionally the missing five percent is a participation or attendance component that was overlooked, and adding it as its own line with a plausible score changes the projection noticeably, because it is five percent that was silently being redistributed across everything else.
The class is graded on total points, not weighted categories. Can I still use this?
Yes, with a translation. Convert each assessment to a weight equal to its share of the total points available in the course. In a 1000-point course, a 150-point midterm is a weight of 15, and a 250-point final is a weight of 25. Enter each score as a percentage of that assessment rather than as raw points. Once converted, the two systems are arithmetically identical, and the needed-on-the-final result is the same. The reason to convert rather than paste raw points is that this page averages within a category, and averaging raw points from assignments of different sizes gives the wrong answer.
How do I handle a lowest-score-dropped policy?
Leave the score out of the line entirely and enter only the ones that will count. Do not enter it and hope the average absorbs it. If the drop happens at the end of the term and you do not yet know which score will be lowest, enter everything for now — the projection will be slightly pessimistic, which is the safer direction to be wrong in — and remove the eventual dropped score once the last assignment in that category is graded. The same applies to a replace-the-midterm-with-the-final policy, which cannot be represented in a fixed weighting at all and needs the calculation redone under both branches.
Does rounding get me from 89.5 to an A?
That is entirely a course policy and there is no general answer. Some instructors round to the nearest whole percent before applying the letter bands, which turns 89.5 into 90 and an A-. Some truncate, which leaves it a B+. Some state explicitly that no rounding occurs. Some round only at their own discretion. This calculator does not round the final figure at all — it prints two decimal places on purpose, so that a result of 89.62 is visible as 89.62 rather than being quietly promoted. If the difference between two letter grades rests on half a point, the question belongs to the instructor and not to a calculator.