Weighted Average Calculator
Calculate a weighted average from a list of values and their weights.
Assumptions used in this calculation
- Weight normalization: Weights are automatically normalized by dividing by their sum, so they don't need to add up to 1 or 100% beforehand.
About this calculator
A simple average treats every value as equally important, but that's wrong whenever some inputs should count more than others, like an exam worth more than a quiz, or a large city's data outweighing a small town's in a regional average, and getting the weighting math right by hand means multiplying each value by its weight and dividing by the total weight without dropping a term. This calculator takes any list of value:weight pairs and computes Σ(value × weight) ÷ Σ(weight), normalizing automatically so the weights don't need to add up to 1 or 100% beforehand, you can enter raw values like 3, 5, 2 instead of pre-converting them to 0.3, 0.5, 0.2. That makes it useful for anything from grade calculations to survey aggregation to financial portfolio weighting, without manually normalizing weights or risking an arithmetic slip in the weighted sum.
Worked example
80 (weight 0.3), 90 (weight 0.5), 70 (weight 0.2)
Result: Weighted average = 83
How to use this
- 1Add each value along with its corresponding weight.
- 2Add as many value/weight pairs as you need.
- 3Read the weighted average, computed as the sum of each value times its weight, divided by the sum of the weights.
Troubleshooting
My weighted average looks the same as a plain average.
That happens when all your weights are equal, a weighted average with identical weights mathematically reduces to a plain average, enter genuinely different weights to see the difference.
Do my weights need to add up to 100 or 1?
No, weights can be any positive numbers (like credit hours, or units sold), the formula divides by the total weight automatically, so the weights don't need to be pre-normalized.
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