Correlation Coefficient Calculator
Calculate Pearson correlation coefficient (r) between two variables. Measures strength and direction of linear relationships.
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How to use this calculator
r ranges from −1 (perfect negative) to +1 (perfect positive). Values near 0 indicate no linear relationship.
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Enter up to 5 paired X and Y values (both sets must have the same count).
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The calculator computes Pearson r, which ranges from −1 to +1.
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Read the interpretation: strong positive (r > 0.7) means both variables rise together.
Frequently asked questions
What does a correlation of 0 mean?
r = 0 means no linear relationship exists between the two variables. There may still be a non-linear relationship.
What is R² (coefficient of determination)?
R² shows the proportion of variance in Y explained by X. For example, r = 0.9 means R² = 81%, so 81% of the variation in Y is explained by X.
Is correlation the same as causation?
No. Correlation only measures association. Two variables can be correlated due to a third confounding variable or pure coincidence.
Pearson Correlation Coefficient Calculator
What does the correlation coefficient measure?
Pearson r measures the strength and direction of the linear relationship between two quantitative variables. Values from −1 to −0.7 indicate strong negative correlation; −0.3 to +0.3 indicate weak or no linear relationship; +0.7 to +1 indicate strong positive correlation.
When to use correlation analysis
Use correlation when you want to know if two continuous variables are related — for example, height and weight, study hours and exam scores, or advertising spend and sales. Always plot a scatter diagram first to check for non-linear patterns that Pearson r would miss.
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