Overview
What Is a Confidence Interval Calculator?
This tool calculates a confidence interval range for a sample mean, showing the range where the true population mean likely falls.
Calculate a confidence interval for a sample mean.
This tool calculates a confidence interval range for a sample mean, showing the range where the true population mean likely falls.
Useful for statistics coursework and research involving sample-based inference about a population.
Input these values from your sample.
Input these parameters.
The range updates automatically.
A range of values that likely contains the true population parameter, with a specified level of confidence.
If you repeated the sampling process many times, about 95% of the resulting intervals would contain the true population mean.
Yes, larger samples generally produce more precise (narrower) confidence intervals.
CI = Sample Mean ± (Z-score × (Standard Deviation ÷ √Sample Size))
Approximately 1.96 for a two-tailed 95% confidence interval.
No, calculations happen entirely in your browser.
Higher confidence (like 99%) widens the interval, trading precision for greater certainty.
Yes, confidence intervals are commonly reported alongside sample statistics in research findings.
This assumes a reasonably normal distribution or sufficiently large sample size for the normal approximation to apply.
Yes, completely free with no sign-up required.