Weighted Average Calculator
Calculate a weighted average from values and weights using number or percent weights, with a full row breakdown.
Values and weights
Add a value and a weight on each row. Blank rows are ignored.
Weighted average
81.11
Total weighted sum divided by the total weight.
Total weighted sum
730.00
Sum of every value multiplied by its weight.
Total weight
9.00
All weights added together.
Rows included
3
Complete rows used in the calculation.
(90×3 + 80×4 + 70×2) ÷ (3 + 4 + 2) = 730 ÷ 9 = 81.11Breakdown
Row-by-row contribution
Each row contributes its value multiplied by its weight to the weighted sum. The weight share shows how much each row influences the final result.
| Row | Value | Weight | Value × Weight | Weight share |
|---|---|---|---|---|
| Math | 90 | 3 | 270.00 | 33.33% |
| Science | 80 | 4 | 320.00 | 44.44% |
| History | 70 | 2 | 140.00 | 22.22% |
| Total | 9.00 | 730.00 | 100% |
How it works
Weighted average formula
A weighted average multiplies each value by its weight, adds the results, then divides by the sum of the weights. Larger weights pull the result toward their values.
Weighted average
Weighted Average = Σ(value × weight) ÷ Σ(weight)The core formula. The total weight in the denominator normalizes the result, so weights do not have to total 100.
Total weighted sum
Weighted Sum = Σ(value × weight)This is the numerator. Each value is scaled by its weight before everything is added together.
Weight share
Share = weight ÷ Σ(weight) × 100The share shows how much influence each row has. For non-negative weights the shares always add up to 100%.
Examples
Weighted average examples
Number weights (credit hours)
Grades 90, 80, 70 with credit weights 3, 4, 2
(90×3 + 80×4 + 70×2) ÷ (3 + 4 + 2) = 730 ÷ 9
81.11
Number mode treats weights as plain multipliers like credit hours.
Percent weights (grades)
Scores 90, 80, 70 with weights 50%, 30%, 20%
(90×50 + 80×30 + 70×20) ÷ (50 + 30 + 20) = 8300 ÷ 100
83.00
Percent weights that total 100 behave like a standard weighted grade.
Percent weights that do not total 100
Values 10, 20 with weights 2, 1
(10×2 + 20×1) ÷ (2 + 1) = 40 ÷ 3
13.33
The result is normalized by the total weight, not forced to 100.
Zero weight
Values 100, 50 with weights 0, 1
(100×0 + 50×1) ÷ (0 + 1) = 50 ÷ 1
50.00
A zero weight contributes nothing, so only the second value counts.
Guide
What the results tell you
Weighted average
The single number that represents your data when some values matter more than others.
Weighted sum
The running total of every value multiplied by its weight, before dividing.
Total weight
The sum of all weights. This is the denominator that normalizes the result.
Percent weights
Percent weights work even when they do not total 100, because the total weight does the normalizing.
Grades and scores
Enter each score as a value and its weighting as the weight to estimate a weighted grade.
Zero and negative
Zero weights contribute nothing, values can be negative, and negative weights are not allowed.
FAQ
Weighted average calculator questions
Multiply each value by its weight, add those products together, then divide by the sum of the weights. In formula form: Weighted Average = sum(value × weight) ÷ sum(weights). Values with higher weights move the result more than values with lower weights.
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Related reading
Learn the formula, assumptions, examples, or context behind this tool.