Points-based or weighted? It changes the answer
There are two ways a course grade gets built, and most students do not know which one they are in until they check.
A points-based course adds everything up out of a shared total. Sixty homework points, 200 exam points, 40 participation points — you earned 262 out of 300, so you have an 87.3%. Weight comes from how many points a thing is worth, not from a percentage in the syllabus.
A weighted-category course groups work into buckets with fixed percentages: homework 20%, quizzes 20%, midterm 25%, final project 35%. Your average within each bucket is what counts, and how many items are in a bucket does not change its influence at all. Ten homework assignments and one midterm can be worth the same.
To tell them apart, look at your syllabus for a percentage list that adds to 100. If it is there, you are weighted. If the syllabus lists point values instead, you are points-based.
The same course, both ways
Homework 92%, quizzes 78%, midterm 81%, final project 84%, with the weights above.
- Weighted: (92 × 0.20) + (78 × 0.20) + (81 × 0.25) + (84 × 0.35) = 18.4 + 15.6 + 20.25 + 29.4 = 83.65%, a B.
- Points-based, with homework at 300 points, quizzes at 100, midterm at 150 and the project at 200: (276 + 78 + 121.5 + 168) ÷ 750 = 86.0%, a B+.
Same scores, same course, two and a half points apart and a different letter. The homework you did well on carries more weight when it is worth 300 of the 750 available points than when it is capped at 20% of the grade. This is why entering your work in the wrong mode is the most common way to get a wrong answer here.
The formula
Weighted: G = Σ(sᵢ × wᵢ) ÷ Σwᵢ, where s is your average in a category and w is its weight.
Points-based: G = Σ earned ÷ Σ possible.
If your weights do not add up to 100 — which happens when a category has not started yet, or when a syllabus is simply wrong — we divide by the total weight you entered rather than by 100. That treats the missing weight as "not yet counted" instead of as a zero, which is almost always what you want mid-semester. It is also why our number can differ from a competitor that silently divides by 100 and quietly deflates your grade.
Why this does not match Canvas, Blackboard or PowerSchool
Usually one of three reasons, and all three are worth checking before you trust either number.
First, ungraded work. Learning-management systems differ on whether an assignment that has not been graded yet counts as a zero or is excluded. Excluded is the default in most, which makes your displayed grade optimistic early in the term and is why it can drop sharply the week everything gets marked. Second, dropped scores. If your syllabus drops the lowest quiz, the gradebook may already be applying that and you may not be. Third, categories with nothing in them. An empty category has no average, and how it is handled — skipped, or counted as zero — swings the result by whole letter grades.
Where this stops being reliable
We calculate what you enter. We cannot see your instructor's rounding habits, late penalties applied per-item rather than per-category, or the extra credit that turns up in week fourteen. Rubric-scored work that is not out of a round number needs converting to a percentage before it goes in. And if the number you get lands within a point of a letter boundary, treat it as "about here" rather than as a verdict.