What This Calculator Does
The Pearson correlation coefficient (r) measures the strength and direction of the linear relationship between two variables, x and y. It ranges from -1 (a perfect negative relationship) to +1 (a perfect positive relationship), with 0 meaning no linear relationship at all.
The Formula
r is calculated as [nΣxy − ΣxΣy] divided by the square root of [(nΣx² − (Σx)²)(nΣy² − (Σy)²)], using each x,y pair you enter. Leave optional pairs blank to exclude them.
Interpreting the Result
Values near +1 or -1 indicate a strong linear relationship, while values near 0 suggest little to no linear relationship. Correlation does not imply causation — a strong r only shows that two variables tend to move together, not that one causes the other.
Note: This tool is intended for general educational and planning purposes.