ToolBirch

Standard Deviation Calculator

Population and sample standard deviation, clearly labelled.Math & Statistics

Standard Deviation Calculator

Population (÷ N) and sample (÷ N−1) standard deviation, with mean and variance readouts.

About this tool

Both sigma variants side by side: population (dividing by N) when your data is the entire group, sample (dividing by N-1) when it is a sample of something larger. Variance and mean shown alongside.

How to use the Standard Deviation Calculator tool

  1. Paste the numbers. At least two for a sample sigma.
  2. Read both sigmas. Labelled unambiguously.
  3. Pick the right one. The note explains when each applies.

Supported formats

Input

  • Plain text or file input

Output

  • Converted or analysed output

Inputs are validated before anything is processed. Invalid values and unsupported files are rejected with a clear error instead of failing silently.

Frequently asked questions

Which sigma should I use?

Population sigma for a complete dataset, sample sigma for estimating from a subset.

Why does sample sigma need two values?

The N-1 denominator is undefined for a single value.

Is variance shown?

Yes, population variance, derived from sigma squared.

Privacy

Everything you enter stays in this browser tab. There is no upload endpoint for tool inputs, no account, and no server-side copy of your text or files. Results are produced locally and disappear when you close the page.

No account is required and no file is ever uploaded. See the privacy policy for details about analytics and the limited data this site stores.

Known limitations

  • No confidence intervals or hypothesis testing.

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