Confidence Interval Calculator

Enter a sample mean, standard deviation, sample size, and confidence level to estimate the margin of error and interval.

Interval type

Confidence

Sample mean

Sample size (n)

Sample SD (s)

—Lower bound

—Upper bound

—Margin of error

—Critical value

—Two-sided confidence interval.

How to use this Confidence Interval Calculator

Calculate a z-based confidence interval for a sample mean. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.