Weighted Average Calculator
Combine values that count unequally, such as assignments, exams and modules with different weights or credits.
The formula
Weighted average = Σ(value × weight) ÷ Σ(weight)
Multiply each value by its weight, add the results, then divide by the total of the weights. Because the result is divided by the total weight, weights do not have to add up to 100: percentages, credits, ECTS points, hours or any other positive numbers all work.
Worked example: course components
Homework scored 72 (worth 20%), a midterm 85 (worth 30%) and a final 90 (worth 50%):
(72 × 20 + 85 × 30 + 90 × 50) ÷ (20 + 30 + 50) = (1,440 + 2,550 + 4,500) ÷ 100 = 84.9
A simple average of 72, 85 and 90 would be 82.33, lower because it treats the homework as equal to the final.
Worked example: module credits
Three modules graded on a 1–10 scale: 7.5 (6 credits), 8.0 (4 credits) and 6.5 (5 credits). The weighted average is (7.5 × 6 + 8 × 4 + 6.5 × 5) ÷ 15 = 109.5 ÷ 15 = 7.3.
Things to check
- Use one scale. All values must be on the same scale. Do not mix percentages with letter grades or 1–10 marks.
- Official averages may differ. Institutions can round individual grades before averaging, drop the lowest score, cap resits or use special rules. Your school's calculation is the one that counts.
- GPA. A GPA is a credit-weighted average of grade points, so this calculator can compute one once you have converted each grade to points using your institution's own table.
Common questions
Can a weight be zero?
Yes; a row with zero weight simply has no effect. At least one weight must be above zero.
Is the weighted average used outside school?
Often: average purchase prices across several buys (price weighted by quantity), portfolio returns (weighted by amount invested) and index calculations all use the same formula.