Confidence Interval Calculator – Z-interval
Compute a confidence interval using the Z-interval method. Enter sample stats; we apply the correct formula. For planning only.
Basic statistics
Enter numbers to compute.
How it works
We apply Z-interval formula (z or t, proportion or mean) to your sample data. Result is an interval estimate.
When to use it
Use when reporting survey or experiment results with Z-interval.
Frequently asked questions
When use z vs t?
Use z for known population SD or large n; t for small samples.
Is this for proportions?
We offer both proportion and mean methods.