Math
Weighted Average Calculator
Compute a weighted mean from any list of value-weight pairs. Shows each weight's share, contribution, and the simple average for comparison.
Values and weights
Separate value and weight with a comma, semicolon, or tab. Weights must be zero or positive. Negative values are allowed.
Weighted average
86.4
Simple average for comparison: 85
Pairs
3
Total weight
100
Difference
1.4
Per-pair breakdown (total weight = 100)
| Value | Weight | Share | Contribution |
|---|---|---|---|
| 85 | 20 | 20% | 17 |
| 78 | 30 | 30% | 23.4 |
| 92 | 50 | 50% | 46 |
Frequently Asked Questions about the Weighted Average Calculator
What is a weighted average?
A weighted average multiplies each value by its weight, sums the products, then divides by the total of the weights. It captures the fact that not every value should count the same, the way a final exam might count for 40% of a course grade while quizzes count for 10%.
How do I calculate a weighted average?
Use sum(value x weight) / sum(weight). For grades 90, 80, 70 with weights 50, 30, 20: (90 x 50 + 80 x 30 + 70 x 20) / 100 = 8300 / 100 = 83. Enter the value-weight pairs and the calculator does the math.
Do the weights need to sum to 100?
No. Weights can be any positive numbers. The calculator normalizes them so 50/30/20 and 5/3/2 produce the same weighted average. The "share" column shows each weight as a percent of the total so you can see how much each row contributes.
Can I use weights of zero?
Yes. A row with weight 0 is ignored. That is useful for keeping a value in the list (for comparison) without letting it influence the average. The total of the remaining weights still needs to be positive.
How does the weighted average differ from a simple average?
A simple (arithmetic) average gives every value equal weight. A weighted average lets a single value count more or less based on its importance. The calculator shows both, so you can see how much the weighting shifts the result.