Statistics
Correlation Coefficient Calculator
Quantify the strength and direction of a linear relationship with Pearson’s r plus the supporting covariance and standard deviations.
Quantify linear association between paired lists with Pearson r and R².
Pearson correlation
r = Σ((x − x̄)(y − ȳ)) / [(n − 1) sₓ sᵧ]
Standard deviations sₓ and sᵧ come from the same datasets, so r stays bounded between −1 and 1 and highlights how tightly the paired values move together.
How to use
- Paste X values and Y values in the same order.
- Ensure each list has at least two numeric entries.
- Review r, R², covariance, and each sample standard deviation.
Example
Input: X = 12, 18, 25, 39; Y = 22, 32, 38, 55
Output: r ≈ 0.99, R² ≈ 0.98, Covariance ≈ 107.8
FAQ & notes
How does this differ from regression?
Correlation measures strength of association only. If you also need slope and predictions, jump to the linear regression calculator.
Why does r sometimes report 0?
If one list has no variation (all values identical) the standard deviation is zero, so Pearson r cannot be computed and the calculator reports 0 as a neutral result.