The weighted average formula
Weighted average = Σ(value × weight) ÷ Σ(weight)
Example: stock purchases
You bought 50 shares at $40, 30 shares at $45 and 20 shares at $52. The simple average price ($45.67) is misleading because you bought more shares at the lower price.
- 50 × 40 = 2,000
- 30 × 45 = 1,350
- 20 × 52 = 1,040
- Total: 4,390 ÷ 100 shares = $43.90 average cost per share
Example: grades
Homework 92% (weight 20), quizzes 85% (weight 30) and the final exam 78% (weight 50): (92 × 20 + 85 × 30 + 78 × 50) ÷ 100 = 82.9%. That is the default example in the calculator above.
For class grades with categories, the weighted grade calculator is set up for you. For credit-hour GPAs, use the GPA calculator.
Last reviewed October 2026.
Frequently asked questions
What is a weighted average?
A weighted average gives some values more influence than others. Each value is multiplied by its weight, the products are added, and the total is divided by the sum of the weights.
Do the weights have to add up to 100?
No. Weights can be percentages, credit hours, quantities or any positive numbers. The calculator divides by the total weight, so 3 and 1 give the same result as 75% and 25%.
How is a weighted average different from a normal average?
A normal average treats every value equally, which is the same as giving them all a weight of 1. If one value has a bigger weight, the weighted average moves toward it.
Where are weighted averages used?
Common uses include course grades (tests worth more than homework), GPA (classes weighted by credit hours), the average price paid for shares bought at different prices, and survey results weighted by group size.
Can a weight be zero?
Yes. A weight of 0 simply leaves that value out. At least one weight must be greater than zero, or there is nothing to divide by.