P-Value Calculator - calculatorsee.com


P-Value Calculator

Calculate p-values from test statistics (Z, t, F, or Chi-Square) to determine statistical significance against alpha thresholds.

Calculator Inputs

Test distribution.
Calculated score.
df.

Calculated Results

P-Value (Two-Tailed)
0.0455 (Statistically Significant)
Significance at alpha = 0.05 Reject Null Hypothesis (p < 0.05)
One-Tailed P-Value 0.0228
Test Statistic Input Z = 2.000
Values calculate live as you adjust inputs.

About P-Value Calculator

Measures the probability of obtaining test results at least as extreme as observed results assuming the null hypothesis is true.

What is P-Value Calculator?

Measures the probability of obtaining test results at least as extreme as observed results assuming the null hypothesis is true.

How to Use This Calculator

  1. Select statistical test distribution.
  2. Enter test statistic score.
  3. View one-tailed and two-tailed p-values and rejection conclusion.

The Mathematical Formula & Variables

P-value = 2 * (1 - NormalCDF(|Z|))

Step-by-Step Worked Example

Scenario: Z = 2.00 in a two-tailed test.

  1. Tail area above 2.00 is 0.02275.
  2. Double for two tails: 2 * 0.02275 = 0.0455.
  3. Since p = 0.0455 < 0.05, the result is statistically significant.

Result: p = 0.0455

Frequently Asked Questions

What is the standard threshold for statistical significance?

The most widely used cutoff is alpha = 0.05 (5%), meaning there is less than a 1 in 20 chance the observed effect was random noise.