How it works
Measure linear association in paired observations. Both series need equal length and nonzero variance; correlation does not establish causation.
r = Σ[(x−x̄)(y−ȳ)] / √[Σ(x−x̄)²Σ(y−ȳ)²]
Worked example
Show example inputs and result
First series: 1 2 3 4 5 · Second series: 2 4 5 4 5.
- Result
- 0.77459667
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