P-Value Calculator

Two-tailed, left-tailed, and right-tailed p-values from a z-statistic.

Calculator Numbers & Math Updated Apr 20, 2026
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How to Use
  1. Enter a z-statistic.
  2. All three tail p-values and significance at α=0.05 are shown.
Input
p-values

Approximation

Φ(z) CDF
Abramowitz & Stegun series — accurate to ~7 decimals
Two-tailed
p = 2 · (1 − Φ(|z|))

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