Weighted Average Calculator
The Weighted Average Calculator combines values that carry different weights — like grades worth different credits, or investments in different amounts. Each value is multiplied by its weight before the total is divided by the sum of all weights.
What this means
A weighted average gives different values different influence. A final grade might be 20% homework and 80% exam — the exam matters four times more. Weights are the importance of each value.
How we calculate it
Formula
Weighted average = Σ(value × weight) ÷ Σ(weight).Worked example
Score 90 weighted 1, score 70 weighted 3:
- 1Weighted sum = 90×1 + 70×3 = 300
- 2Total weight = 1 + 3 = 4
- 3Weighted average = 300 ÷ 4 = 75
Important assumptions
- Weights must be zero or positive.
- Each line holds one pair: value then weight.
Frequently asked questions
When do I use a weighted average?
Whenever values have different importance — grades by credit hours, portfolio returns by amount invested, or surveys weighted by group size.
How is it different from a regular average?
A regular average treats every value equally. A weighted average treats them in proportion to their weights.
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