Compare calculators
Both calculators run independently — change the inputs on either side to compare results.
P-Value Calculator
Convert a z-score (or any standard-normal test statistic) into a p-value for a one- or two-tailed hypothesis test, then see it visualised as the shaded tail area on the standard normal curve. The smaller the p-value, the stronger the evidence against the null hypothesis — reject H₀ when p drops below your significance threshold (commonly 0.05).
Red shaded area is the rejection region — the probability mass in the tail(s) at least as extreme as your test statistic. A significant result means this red area is smaller than your significance level α.
Confidence Interval Calculator
Computes the range of values likely to contain a true population mean at your chosen confidence level. Use it when reporting survey results, clinical trial outcomes, or any estimate derived from a sample.
Key differences
| P-Value Calculator | Confidence Interval Calculator | |
|---|---|---|
| Category | Statistics | Probability |
| Inputs required | 2 | 5 |
| Result | p-value | Margin of Error (±) |
| What it does | Convert a z-score (or any standard-normal test statistic) into a p-value for a one- or two-tailed hypothesis test, then see it visualised as the shaded tail area on the standard normal curve. The smaller the p-value, the stronger the evidence against the null hypothesis — reject H₀ when p drops below your significance threshold (commonly 0.05). | Computes the range of values likely to contain a true population mean at your chosen confidence level. Use it when reporting survey results, clinical trial outcomes, or any estimate derived from a sample. |