Standard Deviation
Variance and standard deviation, sample or population.
Enter values
—
—
Step by step
The formula
σ = √( Σ(xᵢ − μ)² / N )
Standard deviation measures how far values typically sit from the mean, in the same units as the data. Squaring the deviations stops positives and negatives cancelling; the final square root brings the answer back to a readable scale. Sample data divides by n−1 to correct for underestimating the spread of the wider population.
All calculations run locally in your browser and update instantly as you type.
Example calculations
Common questions this calculator answers — select one to load its values.
Related calculators
Frequently asked questions
Sample or population?+
Use sample (divide by n−1) when your data is a subset of a larger group; use population (divide by n) when you have every member.
All calculations run locally in your browser. Nothing you type is sent to a server.