Weighted average calculator
Calculate the weighted average from values and their corresponding weights.
Enter values and weights in the same order (comma separated).
How the calculation works
In a simple average, every value counts equally. In a weighted average, each value has a weight — the larger the weight, the more it pulls the result. It is used in report cards, exam scores and indexes.
average = Σ(value × weight) ÷ Σ(weights)
Multiply each value by its weight, add them up, and divide by the sum of the weights.
Step-by-step example (grades 8, 6, 9 with weights 2, 3, 5)
- Multiply: 8×2 + 6×3 + 9×5 = 16 + 18 + 45 = 79
- Sum of weights: 2 + 3 + 5 = 10
- Average: 79 ÷ 10 = 7.9
The simple average would be 7.67. Because grade 9 has the largest weight (5), the weighted average rises to 7.9.
When to use it
Whenever items differ in importance: a final exam worth more than assignments, courses with different credit hours, or a stage that weighs more in a selection.
Examples
- Grades 7, 5, 10 with weights 1, 1, 3: (7+5+30) ÷ 5 = 42 ÷ 5 = 8.4.
- If all weights are equal, the weighted average equals the simple average.
Frequently asked questions
What if a weight is missing?
We assume weight 1 for any value without a weight.
Simple vs weighted average?
In the simple one all values matter equally; in the weighted one, each counts by its weight. The simple average is the special case where all weights are equal.
Do the weights have to add up to 100 or 10?
No. They can be any numbers — the formula divides by their sum. Weights 2, 3, 5 give the same result as 20%, 30%, 50%.
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Updated on June 18, 2026 · by Rafael Rossi · Methodology & sources