Statistics

Confidence Interval Calculator

Build a confidence interval around a sample mean from the sample size, spread, and chosen confidence level.

Preparing Confidence Interval Calculator

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Input

Enter the sample mean, standard deviation, sample size, and desired confidence level to estimate the interval for the population mean. You will see the result first and the step-by-step solution below.

Input summary

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Step by Step Calculation

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Calculate first and the full working will appear below automatically.

How to use Confidence Interval Calculator

Provide the sample summary and the confidence level, and the calculator will return the interval around the estimated mean.

What this calculator is for

This calculator is for reporting an estimated mean with uncertainty instead of giving a single-number summary without context.

Tips

A higher confidence level usually produces a wider interval.
Larger samples tend to narrow the interval when the spread stays similar.
Read the interval as an estimate for the population mean, not as a guarantee for every individual value.