Weighted Average Calculator with Individual Weights and Contributions

Updated By Unit Conversion Plus

Combine values that have different levels of importance and see how each one contributes to the result.

Enter values and weights

What is a weighted average?

A weighted average gives some values more influence than others. Multiply each value by its weight, add the products, and divide by the total weight.

Weighted average = Σ(value × weight) ÷ Σ(weight)

Relative weights and percentage weights

Relative weights can use any non-negative scale. For example, weights 1, 2 and 3 give the third value three times the influence of the first. Percentage weights express each share out of 100 and must total 100% in this calculator.

Weighted-average example

Suppose scores of 80, 90 and 70 have weights of 20%, 30% and 50%. The weighted average is (80 × 20 + 90 × 30 + 70 × 50) ÷ 100 = 78.

Where weighted averages are used

Weighted averages are common in course grades, investment returns, price indexes, survey summaries and combined performance measures. The chosen weights should represent the actual importance, quantity or share of each value.

Zero and missing weights

A zero-weight entry has no effect on the final result. A missing weight is different from zero and should be corrected rather than silently ignored. Negative weights are excluded because they require a specialised interpretation.

Frequently asked questions

Do relative weights need to total 100?

No. Relative weights are automatically normalised by dividing each weight by their total.

Why must percentage weights total 100%?

A percentage-weighted set should describe the complete allocation. Requiring 100% helps identify missing or duplicated shares.

Can one of the weights be zero?

Yes. That entry contributes nothing to the result, provided the total of all weights is greater than zero.

Is a weighted average always between the smallest and largest value?

Yes, when every weight is non-negative and the total weight is positive.