Standard Deviation Calculator
Paste any list of numbers to get the standard deviation, variance and mean — population and sample side by side.
Reviewed by the OmniCalc teamMethod verified 2026-07-01
8 values
2.4494897
Sample standard deviation 2.4494897- Population std. dev. (σ)
- 2.2912878
- Sample variance (s²)
- 6
- Population variance (σ²)
- 5.25
- Mean (x̄)
- 4.5
- Count (n)
- 8
- Sample std. dev. (s)
- 2.4494897
Show steps
- Mean x̄ = 36 ÷ 8 = 4.5.
- Sum of squared deviations Σ(x − x̄)² = 42.
- Population variance σ² = Σ(x − x̄)² ÷ n = 42 ÷ 8 = 5.25; σ = √σ² = 2.291288.
- Sample variance s² = Σ(x − x̄)² ÷ (n − 1) = 42 ÷ 7 = 6; s = 2.44949.
How to use the standard deviation calculator
- 1Type or paste your data set — separate values with spaces, commas or new lines.
- 2Read the sample standard deviation up top, with the population value and both variances below.
- 3Open Show steps to see the mean, the squared deviations and the divisor used.
σ vs s in one line
Same spread, two divisors: σ divides the squared deviations by n(you have the whole group), while s divides by n − 1(you’re estimating from a sample). For large data sets the two nearly coincide.
Frequently asked questions
Population or sample — which should I use?
Use the population value (σ) when your numbers are the entire group you care about. Use the sample value (s) when they are a sample drawn from a larger population you want to estimate — the divisor n − 1 corrects for the bias of estimating from a sample.
What is variance versus standard deviation?
Variance is the average of the squared distances from the mean. Standard deviation is its square root, which brings the figure back to the original units — that is why it is the more quotable of the two.
Why square the deviations?
Squaring makes every deviation positive so they don't cancel out, and it weights larger gaps more heavily. Taking the square root at the end undoes the units change.