Correlation Coefficient Calculator
Enter two lists of paired numbers (same length, separated by commas or spaces) to calculate the Pearson correlation coefficient.
Last updated: August 30, 2026
Frequently asked questions
What does a correlation coefficient of 1 or -1 mean?
A correlation of exactly 1 means the two variables have a perfect positive linear relationship (as one increases, the other increases proportionally); -1 means a perfect negative linear relationship (as one increases, the other decreases proportionally). Real-world data rarely hits exactly 1 or -1.
Does correlation prove causation?
No - two variables can be strongly correlated without one causing the other, due to coincidence, a shared underlying cause, or reverse causation. Correlation only measures whether two variables tend to move together, not why.
What's considered a 'strong' correlation?
There's no universal cutoff, but a common rough guide is: 0.8+ very strong, 0.6-0.8 strong, 0.4-0.6 moderate, 0.2-0.4 weak, and below 0.2 very weak or none - though what counts as "strong enough" varies a lot by field (social sciences vs. physical sciences, for example).
Is a 'Pearson correlation calculator' or 'Pearson coefficient calculator' the same as this tool?
Yes - "Pearson" refers to the Pearson product-moment correlation coefficient, which is the standard correlation measure this calculator computes. It's the most common type of correlation people mean by "correlation" without further specification.
Is an 'r correlation calculator' the same as this tool?
Yes - "r" is the standard symbol for the Pearson correlation coefficient, so an "r correlation calculator" is asking for the same value this tool computes.