Updated
Using P value calculator
Convert a standard-normal z statistic into one-sided and two-sided p-values.
This is a z-test probability calculation only, not a t, chi-square, or F-test. A p-value is not the probability that the null hypothesis is true. Choose the test and tail before observing results. Normal scores are limited to −37.5 through 37.5. Small p-values are computed from the tail directly, without subtracting nearly equal numbers.
A worked example
With z statistic = 1.959963984540054, the two-sided normal p-value is 0.05.
Before you use the result
This is a z-test probability calculation only, not a t, chi-square, or F-test. A p-value is not the probability that the null hypothesis is true. Choose the test and tail before observing results. Normal scores are limited to −37.5 through 37.5. Small p-values are computed from the tail directly, without subtracting nearly equal numbers.
Example results for z statistic
These examples use the formula above. They are reference calculations, not recommended settings.
| Z statistic | Two-sided normal p-value |
|---|---|
| 0.979981992270027 | 0.327095007691 |
| 1.959963984540054 | 0.05 |
| 3.919927969080108 | 0.0000885754383215 |
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ToolOctopus. “P value calculator.” Updated 2026-09-26. https://tooloctopus.com/p-value-calculator.
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