Confidence Interval for a Correlation Calculator
Find the confidence interval for a correlation coefficient. Enter the correlation, the sample size and the confidence level.
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Why a correlation needs an interval
A correlation from a sample is only an estimate of the true correlation in the population. The confidence interval shows the range of values that are consistent with your data, so you can tell a precise estimate from a shaky one. Smaller samples give wider intervals.
How it is calculated
The interval is built with the Fisher r-to-z transformation, which makes the sampling distribution roughly symmetric, then the endpoints are converted back to the correlation scale. This is why the interval around r is not symmetric, especially for correlations far from zero.
Frequently asked questions
What if the interval includes zero?
If the interval spans zero, the correlation is not statistically significant at that confidence level: the data are consistent with no relationship.
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