What is a correlation calculator?
Pearson’s r summarizes the direction and strength of a linear relationship between two quantitative variables. It ranges from −1 for perfect negative linear association to +1 for perfect positive association.
Use this page for a transparent calculation, then compare the result with the Linear Regression Calculator when a different view of the same data would be useful.
How does this correlation calculator work?
The calculator centers both variables at their means, compares paired deviations, and scales the cross-product by the variation in each list.
Before interpreting spread or position, it can help to check the center with the Coefficient of Variation Calculator. Every tool states its assumptions so results can be reproduced.
How to use this calculator
- Enter the requested numbers in the labeled fields.
- Review unit, sample, confidence, or test choices when shown.
- Select Calculate Correlation.
- Read the main result, supporting facts, and method note.
- Use Copy, Download, or Print when you need to keep the result; select Reset to start over.
If you edit any input after calculating, the old result is marked stale and hidden until you calculate again.
How should you interpret the result?
The sign gives direction and the absolute value gives linear strength. R² is the squared correlation, but it should not automatically be read as a causal effect.
For another useful perspective, open the Standard Deviation Calculator; it answers a related question without changing the values you entered here.
Assumptions and limitations
Correlation is sensitive to outliers, can hide curved relationships, and does not establish causation. Each x-value must be paired with the correct y-value.
Consider the Z-Score Calculator for a complementary summary and the Chi-Square Calculator when your question involves another statistical property. No single statistic describes every important feature of a data set.
Frequently asked questions
Sources and methodology
The formulas and cautions on this page are documented so the calculation can be checked against authoritative statistical guidance.