Weighted Mean Calculator
Calculate a weighted average where observations carry different importance.
About Weighted Mean Calculator
Each value contributes in proportion to its weight, so the weighted mean shifts toward heavily weighted observations. When all weights are equal it reduces to the arithmetic mean. Using an unweighted mean where observations represent different sample sizes is one of the most common analytical errors, and it systematically misrepresents the aggregate.
Formula
Weighted Mean
Weighted mean = Σ(value × weight) ÷ Σweight
- weight
- Relative importance or frequency of each observation
Worked example
With the default values below, Weighted Mean Calculator returns Weighted Mean of 78.00000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Value 1
- 80
- Weight 1minimum 0
- 3
- Value 2
- 92
- Weight 2minimum 0
- 1
- Value 3
- 68
- Weight 3minimum 0
- 2
Results
- Weighted Mean
- 78.00000
- Simple Arithmetic Mean
- 80.00000
- Total Weight
- 6.000
- Difference From the Simple Mean
- -2.00000
- Share Held by the Largest Weight
- 50.00%
Step by step
- 1Values used
- 2Weighted Mean
- 3Weighted Mean= 78.00000
- 4Simple Arithmetic Mean= 80.00000
- 5Total Weight= 6.000
- 6Difference From the Simple Mean= -2.00000
- 7Share Held by the Largest Weight= 50.00
Assumptions and limits
- The result is derived only from the 6 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Weighted Mean calculated?
Weighted mean = Σ(value × weight) ÷ Σweight Each value contributes in proportion to its weight, so the weighted mean shifts toward heavily weighted observations. When all weights are equal it reduces to the arithmetic mean.
Why does Weighted Mean matter?
Using an unweighted mean where observations represent different sample sizes is one of the most common analytical errors, and it systematically misrepresents the aggregate.
What values do I need to enter?
This calculator takes 6 inputs: Value 1, Weight 1, Value 2, Weight 2, Value 3, Weight 3. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.