When to use this calculator
Combine three values using non-negative weights. Weights do not need to sum to 100, but at least one must be positive.
Explore the descriptive statistics calculators for other questions in this topic. For a related calculation, use the Z Score Calculator: Express a value’s distance from the mean in standard deviations.
PUTTING IT INTO PRACTICE
Weighted Mean: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| First value | 70 |
| First weight | 20 |
| Second value | 80 |
| Second weight | 30 |
| Third value | 90 |
| Third weight | 50 |
| Result | 83 |
- Check the input labels and enter the example values above.
- Apply the relationship: Weighted mean = (a×x + b×y + c×z) ÷ (x+y+z).
- The result is 83 , rounded for display.
How to interpret your result
Weights do not need to sum to 100, but at least one must be positive.
The mean, median, range and standard-deviation tools accept variable-length lists with their limits stated. Choose a sample or population denominator appropriately. A summary statistic does not validate the sampling process or explain causation.
Frequently asked questions
Should I use sample or population standard deviation?
Use population deviation for the complete population being described. Use the sample form when estimating variability from a sample under suitable assumptions.
How do I use the weighted mean calculator?
Enter first value, first weight, second value, second weight, third value, third weight. The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Weighted mean = (a×x + b×y + c×z) ÷ (x+y+z).
What should I check before using the result?
Weights do not need to sum to 100, but at least one must be positive.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see NIST: exploratory data analysis ↗. This is a topic reference, not an external review or endorsement of this tool.
Calculators Map editorial process · Updated · Methods and limitations