Variance Calculator
Calculate population and sample variance for any dataset.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Variance Calculator
Enter your dataset as comma or space separated values. The calculator instantly shows both population variance (divides by n) and sample variance (divides by n-1). Sample variance uses Bessel's correction and is the standard choice when your data represents a sample from a larger population.
The breakdown also includes the mean and count. Use Copy to grab the result or Share to send a pre-filled link.
About Variance
Variance measures how far data points are spread from their mean. It is computed as the average of squared deviations. Because deviations are squared, variance is in squared units of the original data. Take the square root of variance to get standard deviation, which is in the same units as the data and often easier to interpret. Variance is central to probability theory, inferential statistics, and portfolio risk analysis in finance.
Frequently Asked Questions
Why divide by n-1 instead of n?
Dividing by n-1 (Bessel's correction) produces an unbiased estimate of the population variance when calculated from a sample. Dividing by n underestimates the true variance. The distinction matters most with small samples.
What is the relationship between variance and standard deviation?
Standard deviation is the square root of variance. Variance is in squared units, making it harder to interpret directly. Standard deviation returns to the original units of your data and is more commonly reported.
Can variance be negative?
No. Variance is the sum of squared deviations divided by n or n-1. Since squared values are always zero or positive, variance is always zero or positive. A variance of zero means all values in the dataset are identical.