Confidence Interval Calculator for a Sample Mean

How this calculator works

This educational estimate uses a two-sided normal critical value for the selected confidence level.

Change one assumption at a time to see which inputs have the greatest effect on the estimate.

Worked example

A mean of 50, standard deviation of 10, and sample size of 100 gives an approximate 95% interval of 48.04 to 51.96.

Limitations

This normal approximation is intended for sufficiently large, representative samples and is not a substitute for statistical study design or professional analysis.

Review this educational estimate against current quotes, official information, and your own budget before making a financial decision.