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.
Related calculators
If the next question is close to this one, these are the best pages to open next.
Math
Use OmniCalc's sample size calculator to estimate how many observations you need for a target margin of error at a chosen confidence level.
Math
Use OmniCalc's p-value calculator to convert a z-score into a quick p-value for left-tailed, right-tailed, or two-sided tests.
Math
Use OmniCalc's z-score calculator to see how far a value is from the mean in standard-deviation units.
Math
Use OmniCalc's standard deviation calculator to measure how spread out a list of numbers is with either sample or population mode.