Calculate p-value from Z-score or test statistic. Determine statistical significance with one-tailed and two-tailed p-value calculations.
Enter your Z-score to calculate the corresponding p-value and significance level.
Get our free PDF with p-value interpretation guidelines, hypothesis testing steps, and decision rules.
The p-value helps you determine the significance of your results in hypothesis testing. It represents the probability of obtaining results at least as extreme as observed, assuming the null hypothesis is true.
P-value ≤ α: Reject the null hypothesis
Your results are statistically significant. The observed effect is unlikely due to chance.
P-value > α: Fail to reject the null hypothesis
Your results are not statistically significant. The observed effect could be due to chance.
One-Tailed Test
Use when you have a specific direction for your alternative hypothesis (greater than or less than).
Two-Tailed Test
Use when you want to detect any difference from the null hypothesis, regardless of direction.