What a weighted average is
A weighted average is a mean where not every value counts equally. Each grade carries a weight that reflects how much it matters, so a grade with a large weight pulls the result harder than one with a small weight. You see it everywhere some pieces of work matter more than others: a final exam worth 40% of the course, a higher-credit class in college, or a performance metric that counts more than the rest of the scorecard.
The contrast with a simple average is easy to picture. A simple average adds up every grade and divides by how many there are, so all grades count the same. A weighted average multiplies each grade by its weight, adds those products, and divides by the sum of the weights. When all weights are equal, the two give the same number; when the weights differ, the weighted result leans toward the grades that carry the most weight.
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How to use the calculator
- Type the first grade and its weight (or credit) into the first row. The assessment name is optional and just helps you keep track.
- Repeat on each row for your remaining grades and their weights.
- Use + Add row to include more assessments, and the ✕ button to drop one you no longer need.
- Read the live results: the weighted average on the main card and the total weight right beside it.
There’s no “calculate” button to press — the average updates as you type.
The formula
The weighted average is:
Average = Σ(grade × weight) / Σ(weight)
In words: multiply each grade by its weight, add up those products, and divide by the sum of all the weights. The calculator always divides by the real sum of the weights you enter, not by 100. That’s why your weights don’t have to add up to 100 for the result to be right: if you use credits (say 3, 4, and 2), the formula works exactly the same.
Worked example
A course has three assessments with these weights:
| Assessment | Grade | Weight |
|---|---|---|
| Midterm 1 | 90 | 30 |
| Midterm 2 | 80 | 30 |
| Final exam | 70 | 40 |
Applying the formula:
- Numerator: 90×30 + 80×30 + 70×40 = 2700 + 2400 + 2800 = 7900
- Denominator: 30 + 30 + 40 = 100
- Weighted average: 7900 / 100 = 79
The simple average of the same grades would be (90 + 80 + 70) / 3 = 80. The weighted result is lower because the weakest grade (70) is the one that carries the most weight — the final exam is worth 40%.
GPA and credits
In college your average is usually reported as a GPA (grade point average), using each course’s credits as the weight. You first convert every letter grade to grade points (on a 4.0 scale, A = 4.0, B = 3.0, C = 2.0, and so on), multiply the points by the credits, and divide by the total credits. It is the same weighted-average formula, with “weight = credits” and “grade = grade points.”
| Course | Credits | Points |
|---|---|---|
| Calculus I | 4 | 4.0 |
| History | 3 | 3.0 |
| Chemistry | 3 | 3.7 |
| English | 2 | 3.3 |
Sum of points times credits: 42.7. Total credits: 12. GPA = 42.7 / 12 ≈ 3.56.
Frequently asked questions
When should I use a simple average versus a weighted one?
Use a simple average when every grade counts the same and you just want the mean of a set. Use a weighted average when some assessments matter more than others: midterms versus a final, courses with different credit hours, or metrics with different importance.
Do the weights have to add up to 100?
No. The calculator divides by the real sum of the weights, so the answer is correct whether they add up to 100, to 10, or to anything else. Weights summing to 100 is just convenient because each one then reads directly as a percentage. If you use credits (3, 4, 2…) the average still comes out right.
How do I compute my GPA with credits?
Convert each grade to grade points using your school’s scale, put the points in the grade column and the credits in the weight column. The weighted average shown is your GPA. Always confirm the conversion scale with your institution, since it varies from school to school.
Does the calculator round?
It displays the result with up to two decimals so it stays readable, but it computes at full internal precision. If your school rounds differently — half a point up, for example — treat the shown value as a reference and apply your institution’s official rule.