Question
What does a confidence interval show?
It shows a range of plausible values for the population mean based on the sample statistics you entered.
Math
Use OmniCalc's confidence interval calculator to estimate a plausible range around a sample mean using a chosen confidence level.
Confidence interval calculator
Enter a sample mean, standard deviation, sample size, and confidence level to calculate a quick z-based confidence interval.
Why this result matters
A distinct follow-on stats page for estimating uncertainty around sample means, bridging descriptive stats into inference. Use the tool above to enter a few clear inputs and get a practical answer you can use right away.
This confidence interval calculator helps students, analysts, and everyday users estimate a range around a sample mean without doing the margin-of-error formula by hand. Enter the sample mean, standard deviation, sample size, and confidence level to see the interval instantly.
Formula and method
The calculator uses a z-based confidence interval for a mean: sample mean ± critical value × (standard deviation / square root of sample size).
Example
If the sample mean is 72, the standard deviation is 12, the sample size is 36, and the confidence level is 95%, the interval is about 68.08 to 75.92.
FAQ
Short answers to the questions people often ask before or after using the tool.
Question
It shows a range of plausible values for the population mean based on the sample statistics you entered.
Question
A larger sample reduces the standard error, which usually shrinks the margin of error and tightens the interval.
Question
Higher confidence levels use a larger critical value, so the margin of error increases and the interval becomes wider.
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