Standard Deviation Calculator

Calculate the standard deviation of a set of numbers. Paste or type your values and choose sample or population, and the calculator returns the standard deviation, the variance, the mean, the count and the sum. It updates as you edit the list.

Enter numbers (separated by commas, spaces or new lines)

Standard deviation

2.1381

Count8

Mean5

Variance4.5714

Sum38

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Sources & methodology

Last reviewed January 15, 2026.

Method: Population σ = √(Σ(x−μ)²/N); sample s uses N−1 (Bessel's correction). Both are shown so you can pick the one matching your data.

NIST/SEMATECH e-Handbook of Statistical Methods

How it works

Standard deviation measures how spread out numbers are around the mean. First find the mean, then the average of the squared differences from the mean (the variance), then take its square root. The sample version divides by n − 1, while the population version divides by n.

Frequently Asked Questions

What is the difference between sample and population?

Use population when your data is the entire group. Use sample when it is a subset used to estimate a larger group; it divides by n minus 1 to correct for bias.

What does a higher standard deviation mean?

A higher value means the data points are more spread out from the mean, while a lower value means they cluster closely around it.

Does it also show variance?

Yes. Variance is shown alongside the standard deviation, the mean, the count and the sum.

Standard Deviation Calculator

How it works

Frequently Asked Questions

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