How it works
Estimate spread from at least two sample observations using the n−1 denominator. The result has the same units as the inputs.
s = √[Σ(x−x̄)²/(n−1)]
Worked example
Show example inputs and result
Numbers: 2 4 4 4 5 5 7 9.
- Sample standard deviation
- 2.13808994
- Sample variance
- 4.57142857
Questions and answers
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method reviewed: October 8, 2026 · Methods & accuracy