Standard Deviation

Work out the population and sample standard deviation, variance and mean for any list of numbers.

Standard deviation of your numbers

Mean: —

Population standard deviation: — · Variance: —

Sample standard deviation: — · Variance: —

Count: — · Sum: —

The population form divides by n, the sample form divides by n − 1. All maths runs locally in your browser.

Paste or type your data set into the box, separated by commas, spaces or new lines.
The mean and both standard deviations are computed instantly.
Use the population figure for a full data set and the sample figure for a sample.

Common questions about the free online standard deviation.

Standard deviation measures how spread out a set of numbers is around the mean. A small value means the values sit close to the average.

The population version divides by the number of values, while the sample version divides by one less to correct for sampling bias.

Use the population figure when you have every value you care about, and the sample figure when your numbers are only a sample of a larger group.

The tool finds the mean, sums the squared differences from that mean, divides by n or by n − 1, and then takes the square root.

Variance is the square of the standard deviation. Both the population and sample variances are shown so you can use either form.

Sample standard deviation needs at least two values, so it stays blank when only one number is entered.

Commas, spaces, tabs and new lines all work, so you can paste a column straight from a spreadsheet.

No. Everything is computed locally in your browser and nothing is transmitted.

Yes. It is completely free and unlimited, with no account, no sign-up and no usage caps.

Last updated: October 10, 2026