What is a variance calculator?
Variance measures spread by averaging squared distances from the mean. Because the deviations are squared, variance is expressed in squared units and gives greater weight to observations farther from the center.
Use this page for a transparent calculation, then compare the result with the Standard Deviation Calculator when a different view of the same data would be useful.
How does this variance calculator work?
The calculator uses a numerically stable one-pass method to find the mean and sum of squared deviations. It divides by n − 1 for a sample or by N for a complete population.
Before interpreting spread or position, it can help to check the center with the Average Calculator. Every tool states its assumptions so results can be reproduced.
How to use this calculator
- Enter the requested numbers in the labeled fields.
- Review unit, sample, confidence, or test choices when shown.
- Select Calculate Variance.
- Read the main result, supporting facts, and method note.
- Use Copy, Download, or Print when you need to keep the result; select Reset to start over.
If you edit any input after calculating, the old result is marked stale and hidden until you calculate again.
How should you interpret the result?
A variance of zero means every value is identical. Larger variance indicates greater spread, but comparison is clearest when data sets use the same measurement units and similar scales.
For another useful perspective, open the Coefficient of Variation Calculator; it answers a related question without changing the values you entered here.
Assumptions and limitations
Variance is sensitive to outliers, and its squared units may be less intuitive than standard deviation. The sample formula also assumes the observations reasonably represent the target population.
Consider the Interquartile Range Calculator for a complementary summary and the Mode Calculator when your question involves another statistical property. No single statistic describes every important feature of a data set.
Frequently asked questions
Sources and methodology
The formulas and cautions on this page are documented so the calculation can be checked against authoritative statistical guidance.