What is the difference?
Total-points grading
Add all points earned and divide by all points possible. Every point counts equally, so bigger assignments carry more influence.
A 90/100 exam and a 9/10 quiz both score 90%, but the exam moves the course grade ten times as much because it has ten times the points.
Weighted category grading
Each category has a stated percentage weight. Homework can be 20% of the course while exams are 50%.
Here the weights, not the raw points, decide influence. A category with few points can matter a lot, and a category with many points can matter little.
Same scores, two different grades
Suppose a course has three categories with these results.
| Category | Points | Category % | Weight |
|---|---|---|---|
| Homework | 198 / 200 | 99% | 20% |
| Quizzes | 40 / 50 | 80% | 30% |
| Exams | 160 / 200 | 80% | 50% |
Total points: (198 + 40 + 160) ÷ (200 + 50 + 200) = 398 ÷ 450 = 88.44%. On the standard scale that is a B+.
Weighted: 99 × 0.20 + 80 × 0.30 + 80 × 0.50 = 19.8 + 24 + 40 = 83.8%. That is a B.
The gap is 4.64 percentage points, and it crosses a letter boundary. Homework holds 200 of 450 points (about 44%) but only 20% of the weight, so the total-points method rewards that 99% much more. Exams also hold about 44% of the points but 50% of the weight, and the 80% there drags the weighted result down.
How to tell which system you have
Look at your syllabus or gradebook. If it lists raw points such as 40/50 and 85/100 and gives one total, you are likely using total points. If it lists category weights such as Homework 20%, Quizzes 30%, and Exams 50%, use a weighted method. Many courses combine the two: points decide the score inside a category, and weights combine the categories.
Common mistakes
- Using points when the syllabus is weighted. This is how the example above overstates the grade.
- Averaging category percentages equally. The average of 99, 80, and 80 is 86.33%, which ignores the weights entirely.
- Weights that do not total 100%. Either a category is missing or the weights are relative. Check before trusting the result.
- Applying weights to raw points. Convert each category to a percentage first, then apply the weight.
Special cases
- Ungraded categories. Some gradebooks ignore a category with no scores and rescale the remaining weights, while others count it as zero until work is graded.
- Dropped lowest score. Removing a low score changes the category percentage before weighting. The Final Grade Calculator has a mode for this.
- Extra credit. The effect depends on where it is added; see how extra credit changes your grade.
Which calculator to use
For a total-points course, use the Grade Calculator or Points Grade Calculator. For category weights, use the Weighted Grade Calculator, and for planning a final exam use the Final Grade Calculator. The full method for each is in how to calculate a weighted grade and how to calculate your current grade.