Standard Deviation Calculator
Calculate population and sample standard deviation and variance.
About this calculator
The Standard Deviation Calculator on NumberCals is a free, mobile-friendly tool for anyone needing to calculate population and sample standard deviation and variance. Enter your values in the form below and the result is computed instantly — no sign-up, no installation, no waiting.
Formula used
σ = √(Σ(xᵢ − μ)² / n); s = √(Σ(xᵢ − x̄)² / (n−1))
What you'll need
- Numbers (e.g. 2, 4, 4, 4, 5, 5, 7, 9)
What you'll get
- Mean
- Population SD (σ)
- Sample SD (s)
- Population Variance (σ²)
- Sample Variance (s²)
Formula
σ = √(Σ(xᵢ − μ)² / n); s = √(Σ(xᵢ − x̄)² / (n−1))
Result
Frequently Asked Questions
Population vs sample SD? +
Use population when you have all data points; use sample (n−1 in denominator) when estimating from a subset.
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