Free Online Calculators

Standard Deviation Calculator

Calculate population and sample standard deviation for any dataset.

Calculator
📊 Results
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Sample Standard Deviation (s)
Count (n)—
Mean—
Population Std Dev (σ)—
Sample Std Dev (s)—
Population Variance (σ²)—
Sample Variance (s²)—
Sum of Squares—

Population vs Sample

Use population std dev (σ) when you have data for the entire population. Use sample std dev (s) when your data is a sample from a larger group — which is almost always the case in research. Sample std dev uses n−1 (Bessel's correction) to avoid underestimating variability.

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