What is the Confidence Interval Calculator?
A confidence interval gives a range that likely contains the true population value. Enter your sample mean, standard deviation and sample size (or the number of successes for a proportion), pick 90, 95 or 99% confidence, and get the interval and margin of error. For small samples it uses the t-distribution automatically.
How to use the Confidence Interval Calculator
- Choose mean or proportion.
- Enter the sample values.
- Pick the confidence level and read the interval.
Why is the interval wider at 99%?
To be more confident that the range contains the true value, it has to be wider.
This Confidence Interval Calculator is 100% free, needs no signup and runs privately in your browser – on phone, tablet or computer.
Last updated: · By NodifyTech