Correlation Coefficient Calculator
Paste paired x, y data to get Pearson's r, R², and a plain-language read on the strength and direction.
How to use it
- Enter paired data One x, y pair per line, separated by a comma or space.
- Read the coefficient See Pearson's r, R² and the number of pairs.
- Interpret it The direction and strength are summarized for you.
Examples
| y = 2x | r = 1 |
|---|---|
| opposite trend | r = −1 |
About this tool
The Pearson correlation coefficient, r, measures how strongly two variables move together in a straight line. It ranges from −1 (a perfect downward relationship) through 0 (no linear relationship) to +1 (a perfect upward relationship). R², the square of r, is the share of variation explained.
Paste your paired data and the calculator reports r, R² and a plain-language read on the strength and direction. Remember that correlation does not prove causation. Everything runs in your browser.
Frequently asked questions
What does the correlation coefficient measure?
Pearson's r measures the strength and direction of a linear relationship between two variables, from −1 (perfect negative) through 0 (none) to +1 (perfect positive).
Does correlation mean causation?
No. A strong correlation shows two things move together, but it does not prove that one causes the other.
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Updated June 12, 2026