Correlation Coefficient Calculator
Enter two equal-length lists of numbers to compute the Pearson correlation coefficient between them.
Strong positive correlation
5
0.8528
0.7273
Strong positive correlation
0.8
Formula
About this calculator
The Pearson correlation coefficient, r, measures how strongly two variables move together in a straight-line relationship. It ranges from −1 to +1: a value near +1 indicates a strong positive relationship (as one variable rises, so does the other), a value near −1 indicates a strong negative relationship, and a value near 0 indicates little or no linear relationship.
Provide two lists of equal length, where each X is paired with the Y on the same position. The calculator also reports r², the coefficient of determination, which is the proportion of variance in one variable explained by the other, along with the slope of the best-fit regression line. Remember that correlation does not imply causation, and Pearson’s r only captures linear relationships — two variables can be strongly related in a curved pattern yet have an r close to zero.
Frequently asked questions
It measures the strength and direction of the linear relationship between two variables. Values near +1 or −1 indicate strong relationships, while values near 0 indicate weak or no linear relationship.
No. Correlation does not imply causation. Two variables can be strongly correlated because of coincidence or a third underlying factor, not because one causes the other.
R-squared is the square of the correlation coefficient. It represents the fraction of the variation in one variable that can be explained by a linear relationship with the other. An r of 0.8 gives an r² of 0.64, or 64%.
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