How it works
Find the root mean square of observations by squaring, averaging and taking the square root. Negative signs disappear when squared.
RMS = √[Σx²/n]
Worked example
Show example inputs and result
Numbers: 2 4 4 4 5 5 7 9.
- Result
- 5.38516481
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