Weighted Average Calculator
Find the weighted average of a list of values and weights, and compare it with the simple average.
Quick answer
A weighted average gives each value a weight reflecting its importance: sum of (value x weight) divided by the sum of the weights. Weights can be any positive numbers, not only percentages.
Weighted Average Calculator
Weighted Average
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Sum of Weights
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Simple Average
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Weighted − Simple
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Rows Used
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Contribution of Each Row
| Row | Value | Weight | Share of weight | Contribution |
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Assumptions & method
- Weighted average = Σ(value × weight) ÷ Σ(weight).
- Simple average = Σ(value) ÷ number of rows, ignoring weights.
- Contribution = value × weight ÷ Σ(weight); the contributions add up to the weighted average.
- Weights must be zero or more with a total above zero. Values may be negative. Rows with both fields blank are ignored.
- Results use exactly the numbers you enter; nothing is rounded, normalised or adjusted beyond the display.
Results are estimates based on the figures you enter. They are not guarantees and not financial advice.
What a weighted average tells you
A weighted average accounts for the fact that not every item matters equally. Each value is multiplied by its weight, the results are added up, and the total is divided by the sum of the weights. The result sits closer to the values with the biggest weights. It is the right tool for grades with different assignment weights, an average purchase price across lots of different sizes or a return across holdings of different sizes. The simple average is shown next to it for comparison, along with each row's share of the total weight and its contribution to the answer.