How it works
Fill in the 4 fields above and Confidence Interval Calculator calculates the result instantly, recalculating as you change any value. The math runs locally in your browser — nothing is sent to a server.
Examples
- Sample mean 100, Standard deviation 15, Sample size 30 → Confidence interval: 94.6323 to 105.3677
Frequently asked questions
How do I use the Confidence Interval Calculator?
Enter your values in the 4 input fields and the result is calculated automatically as you type. Change any value to see the numbers update instantly.
Is my data private?
Yes. The Confidence Interval Calculator runs entirely in your browser. Nothing you enter is uploaded, saved to a server, or shared — it never leaves your device.
Is the Confidence Interval Calculator free?
Yes, it is completely free with no sign-up, no limits and no watermarks. Like every tool on statistics and the rest of the platform, you can use it as often as you like.
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