# Confidence Interval Calculator (z statistics)

## Free Statistics Help Resources

### » Confidence Interval Calculator for μ - Known population standard deviation

Use this calculator if you want to compute a confidence interval for a population mean when the population standard deviation is known, in which case the normal distribution is used. You have information about the sample mean and sample size.

(Observe that for this interval to be meaningful, the distribution of the population being studied needs to be normal, or at least approximately normal).

Sample Mean ($$\bar X$$)
Population St. Dev. ($$\sigma$$)
Sample Size ($$n$$)
Confidence Level
(Ex: 0.99, 0.95, or 99, 95 without '%', etc)

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