Variance Calculator
Calculate the sample or population variance of up to 8 numbers, showing how far your data is spread from its average value.
Only the first this-many values below are included.
Your results
Sample variance divides by n − 1.
Calculation breakdown
- Mean
- x̄ = Σx / n
- Sample variance
- s² = Σ(x − x̄)² / (n − 1)
- Population variance
- σ² = Σ(x − x̄)² / n
Worked example
Weekly sales figures of 12, 15, 9, 18 and 14 units, treated as a sample, give a mean of 13.6 and a sample variance of about 11.3 (units squared).
Assumptions
- Use 'Sample' for a subset of a larger group and 'Population' when every member is included.
- Variance is expressed in squared units of the original data, which is why the standard deviation (same units as the data) is also shown.
How this calculator works
Enter up to 8 numeric values and choose sample or population variance. The tool computes the mean and the average squared deviation from that mean, along with the matching standard deviation for easier interpretation.
Frequently asked questions
Why is variance expressed in squared units?
Variance sums squared differences from the mean, so its units are the square of the original data's units, which is why standard deviation (same units as the data) is often preferred for interpretation.
When should I use population instead of sample variance?
Use population variance only when your values represent every member of the group you care about; otherwise use sample variance.
Is variance affected by outliers?
Yes, because differences from the mean are squared, a single unusually large or small value can noticeably increase the variance.