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Standard Deviation Calculator

Mean, variance and standard deviation for any data set.

Details

Results

Sample std dev (s)
Population std dev (σ)
Mean
Variance (sample)
Count

Computed with standard statistical methods in your browser.

How it works

We compute the mean, then the sum of squared deviations. Population variance divides by n; sample variance divides by n−1 (Bessel’s correction). Standard deviation is the square root of variance.

Sample vs population: use sample (n−1) when your data is a sample of a larger group; use population (n) when it’s the whole group.

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Good to know

FAQs

What’s the difference between sample and population SD?

Sample SD divides by n−1 (for a sample); population SD divides by n (for the entire group).

How do I enter data?

Paste numbers separated by commas, spaces or new lines.

What is variance?

The average squared deviation from the mean; standard deviation is its square root.

Why n−1 for samples?

Bessel’s correction reduces bias when estimating population variance from a sample.

Does it handle decimals and negatives?

Yes — both are supported.