What is this calculator?
Find the two-tailed probability for a standard-normal z statistic.
What can you use it for?
Use it when solving an exercise, checking a result, or working with the particular quantities shown in this form. Find the two-tailed probability for a standard-normal z statistic.
How to use it
- Enter z statistic.
- Select Calculate (or Generate for random tools).
- Read the answer and any additional results below the form. Check the units and the limits of the method.
Formula and method
Two-tailed p = 2 × [1 − Φ(|z|)]
A numerical approximation to the standard-normal cumulative distribution is used.
Worked example
Z statistic: 1.96. The result is 0.04999565 (two-tailed normal p-value).
Assumptions and limits
Normal distribution only. Not a t-test, chi-square test or F-test.
Frequently asked questions
What inputs does the P-value Calculator need?
Use z statistic. Read the answer and any additional results below the form. Check the units and the limits of the method.
What assumptions apply to the P-value Calculator?
Normal distribution only. Not a t-test, chi-square test or F-test.