Standard deviation calculator
Paste your values to calculate standard deviation and a complete descriptive statistics summary.
How do I use this page?
- Paste at least two values.
- Use s for a sample or σ for a population.
- Check quartiles and range before interpreting spread.
What this page does not do: The measure is sensitive to outliers. The sample or population formula must match what the data represents.
Further reading
Theory — what is standard deviation?
Standard deviation measures the typical distance of values in a dataset from their mean. For a sample, the sum of squared deviations is divided by n−1, while for a full population it is divided by n, giving slightly different results for the same numbers. The same data also yields the five-number summary, quartiles, the interquartile range, the range and the mode. The n−1 method is used when the data is a sample meant to estimate the variability of a larger population.
Frequently asked questions
When should I divide by n−1?
Is a small standard deviation always good?
See also
A/B test calculator
Compare two proportions in an A/B test. Calculate conversion rates, difference, uplift, z score, p value and c
A/B test planning — sample size, MDE and duration
Plan a two-proportion experiment, estimate detectable effect and traffic duration.
ACF and PACF autocorrelation calculator
Calculate ACF and PACF across time-series lags. Review the chart, reference bounds and coefficient table.