Grade Calculator
How Weighted Grading Works
In high school, grades were often calculated using a "Total Points" system. If you got 90/100 on a test and 10/10 on homework, you had 100/110 points total.
College and University courses usually use Weighted Averages. This means specific categories are worth a fixed percentage of your grade, regardless of how many points they are worth.
- Example: The Final Exam is worth 30% of your grade.
- Example: Homework is worth 10% of your grade.
In this system, getting 100% on homework is nice, but bombing the Final Exam (worth 3x as much) will destroy your average.
The Mathematical Formula
To calculate a weighted average manually, you multiply each grade ($g$) by its weight ($w$), sum them all up, and divide by the total weight (usually 100 or 1).
Scenario:
- Test 1: 80% (Weight 20%) -> 80 * 0.20 = 16 points
- Test 2: 90% (Weight 20%) -> 90 * 0.20 = 18 points
- Final: 70% (Weight 60%) -> 70 * 0.60 = 42 points
Total: 16 + 18 + 42 = 76% (C Grade).
Even though you got a 90% on one test, the heavy weighting of the Final Exam pulled your average down significantly.
Standard Letter Grade Scale
While every professor is different, here is the standard US GPA scale conversion.
| Percentage | Letter Grade | GPA Point |
|---|---|---|
| 93 - 100% | A | 4.0 |
| 90 - 92% | A- | 3.7 |
| 87 - 89% | B+ | 3.3 |
| 83 - 86% | B | 3.0 |
| 70 - 79% | C | 2.0 |
| < 60% | F | 0.0 |
In a weighted system, missing a single assignment (getting a Zero) can be catastrophic if that assignment has a high weight. If you miss a "Midterm" worth 20%, the maximum grade you can achieve in the class is 80% (a low B), assuming you get 100% on everything else!
Points System vs. Weighted System
How do you know which system your teacher uses? Check the Syllabus.
- Weighted: Look for percentages. "Exams 40%, Homework 20%". Use this calculator.
- Points: Look for totals. "Total points possible in course: 500". In this case, just divide your Total Points Earned by 500.