Standard Deviation Calculator
Calculate standard deviation and variance for population or sample data.
Standard Deviation (σ or s)
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Variance (σ² or s²)
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Mean
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Count (n)
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Standard Deviation Formula
Standard deviation measures how spread out the data is from the mean.
Population Standard Deviation
σ = √[Σ(xᵢ − μ)² / N]
Sample Standard Deviation
s = √[Σ(xᵢ − x̄)² / (n−1)]
Use sample standard deviation when working with a sample from a larger population. Use population standard deviation when you have data for the entire population.