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Standard Deviation Calculator

Calculate population or sample standard deviation, variance, and mean for a list of numbers.

Calculation basis

Data handling

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How it works

Standard Deviation Calculator: a practical guide

A standard deviation calculator measures how far a set of values typically falls from its mean. It lets you choose whether the entered values are the entire population or a sample from a larger group, because those two assumptions use different formulas.

  1. STEP 01

    Paste or type whole or decimal numbers separated by commas, spaces, semicolons, or new lines.

  2. STEP 02

    Choose Population only when the values are the whole group; otherwise choose Sample.

  3. STEP 03

    Calculate to review the standard deviation, mean, variance, and number of values.

What this tool does and its limits

Population standard deviation divides the sum of squared differences by the number of values. Sample standard deviation divides by one less than the number of values, a correction used when a sample estimates a larger population. The calculator uses a stable running calculation for the values you enter. It does not detect outliers, decide whether your data is a sample, run a statistical test, interpret practical importance, or handle localized decimal commas.

Inputs, selected files, and results stay in your browser. The tool does not upload them to Got A Tool or save them to persistent storage.

Questions

Standard Deviation Calculator details

What is standard deviation?

It is a measure of spread: a smaller result means values tend to cluster nearer the mean, while a larger result means they are more spread out.

Should I use population or sample?

Choose Population when your list contains every value in the group you want to describe. Choose Sample when the list is a subset used to estimate a larger group.

Why is sample standard deviation larger?

The sample formula divides by one less than the number of values, which adjusts for estimating a wider population from a limited sample.

Can I paste numbers on separate lines?

Yes. New lines, commas, spaces, and semicolons all separate values in this version.

Keep working

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