🎯
Confidence Interval Calculator
Margin of error and CI for a sample mean.
Enter your details
Results
Confidence Interval
—
Margin of Error
—
How to use the Confidence Interval Calculator
CI = mean ± z* × σ/√n. Larger samples and lower confidence shrink the interval.
Frequently Asked Questions
If you repeated the sampling 100 times, ~95 of the intervals would contain the true mean. Not '95% chance this one does'.