Weighted Average Calculator
Average values where each carries a different weight or importance.
What the Weighted Average Calculator does
A weighted average lets some values count for more than others. Each value is multiplied by its weight, the products are summed, and the total is divided by the sum of the weights. Weights can be percentages, credit hours, quantities or any relative importance.
Formula
Weighted average = Σ(value × weight) ÷ Σ(weight)
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Values | text | Yes | Separate values with commas, spaces or new lines. |
| Weights | text | Yes | One weight per value, in the same order. |
How to use it
- Enter Values and Weights.
- Select Calculate.
Worked example
Coursework 85 (30%), final exam 92 (50%), participation 78 (20%).
- Values
- 85, 92, 78
- Weights
- 30, 50, 20
(85×30 + 92×50 + 78×20) ÷ 100 = 87.1.
Reading the result
- The result always falls between the smallest and largest value, however the weights are set.
- Only the relative size of the weights matters: 2 and 3 give the same answer as 20 and 30, or 40% and 60%.
Common mistakes
- Dividing by the number of items instead of by the sum of the weights, which turns a weighted average back into a plain one.
- Assuming the weights must total 100. They are normalised automatically, so any consistent scale works.
Frequently asked questions
Do the weights need to add to 100?
No. They are normalised automatically, so 30/50/20 and 3/5/2 give the same answer.