Difference of Means Confidence Interval Calculator
Enter the mean, SD and size of each sample.
Result
How to use
- Enter your values in the fields above.
- Press Calculate to see your result instantly.
- Use the Share button to copy a link to your result.
About this calculator
When comparing two groups — a treatment vs. control group, two product variants, two time periods — the raw difference between their sample means only tells half the story. A confidence interval for the difference of means quantifies the uncertainty around that gap, built from each group's mean, standard deviation, and sample size using the standard error of the difference.
This is a foundational technique in inferential statistics, used in A/B testing to decide whether an observed lift is likely real or just noise, in clinical trials to compare treatment effects, and in scientific research generally whenever two independent samples need to be compared rather than just eyeballed side by side.
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