Weighted Average Calculator

Calculate an average when values contribute with different weights

Enter the same number of values and weights, separated by commas, spaces or new lines.

Your result will appear here.

About the Weighted Average Calculator

When some values count more than others, a simple mean gives the wrong emphasis. This calculator applies a separate weight to each value so course grades, portfolio results and composite scores reflect their intended importance.

The weights must represent the intended importance or quantity. Using percentages that do not match the real weighting scheme can produce a mathematically correct but conceptually wrong result.

How to Use the Weighted Average Calculator

  1. Enter each value to be averaged.
  2. Enter the corresponding weight for every value.
  3. Confirm that all weights use the same basis, such as percentages or relative units.
  4. Calculate the weighted mean and compare it with a simple average if you want to see how much the weights change the result.

How the Calculation Works

Weighted average = Σ(value × weight) ÷ Σ(weights). When weights already sum to 100%, the denominator is 100 if the percentages are entered directly.

Each contribution is proportional to its weight, so a value with twice the weight has twice the influence on the final average.

Worked example

Weighted Average Calculator Worked Example

Scores 80, 90 and 70 with weights 20%, 50% and 30%

Weighted contributions are 80×0.20=16, 90×0.50=45 and 70×0.30=21. Add them: 16+45+21=82. The weighted average is 82.

Result guide

Understanding Your Weighted Average Calculator Result

The weighted average reflects both performance and importance. A high value with a small weight may affect the result less than a moderate value with a large weight.

Before you rely on the answer

Assumptions and Limitations

  • Each value is paired with the correct weight.
  • Weights are non-negative and use a consistent scale.
  • The chosen weights genuinely represent importance, frequency or quantity.

Practical tip

Using This Result in Practice

Before calculating, write each value and weight in one row. Misaligned value-weight pairs are one of the easiest ways to get a plausible-looking but wrong weighted average.

Related calculations

Useful Calculations to Continue With

If every observation should count equally, use the Average Calculator instead.

For course assignments and category weights, the Grade Calculator provides a more education-specific workflow.

Common questions

Weighted Average Calculator FAQ

Do weights need to add to 100%?

Not necessarily. The general formula divides by the sum of weights, so relative weights can work even when they do not total 100.

What is the difference between weighted and simple average?

A simple average gives every value equal influence, while a weighted average scales influence by the assigned weights.

Can a weighted average fall outside the input range?

With non-negative weights, it should lie between the minimum and maximum input values.