P-value Calculator
Please provide any one value below to compute p-value from z-score or vice versa for a normal distribution.
Calculate p-values from z-scores or find z-scores from p-values for normal distributions.
About P-Values
Z-Score
Number of standard deviations from the mean
Z = (X - μ) / σ
P-Value Types
- Left-tail: P(X < Z)
- Right-tail: P(X > Z)
- Two-tailed: P(|X| > |Z|)
Significance Levels
- • p < 0.05: Significant
- • p < 0.01: Highly significant
- • p < 0.001: Very highly significant
Common Z-scores
Z = 1.645 → p = 0.05 (one-tail)
Z = 1.96 → p = 0.05 (two-tail)
Z = 2.33 → p = 0.01 (one-tail)
Z = 2.576 → p = 0.01 (two-tail)