Z-Score Table
Look up cumulative probabilities from the standard normal distribution (z-table)
P(Z < 1.96)
0.9750
97.50%
97.5% of data falls below z = 1.96
0.9750
0.0250
0.0500
2σ
Standard Normal Table — P(Z < z)
| z | 0.00 | 0.01 | 0.02 | 0.03 | 0.04 | 0.05 | 0.06 | 0.07 | 0.08 | 0.09 |
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About Z-Score Tables
A z-score table (also called a standard normal table) shows the cumulative probability P(Z < z) for a given z-score. It is used to find probabilities and percentiles in hypothesis testing, confidence intervals, and quality control.
P(Z < z) = Φ(z) = (1/√(2π)) ∫-∞z e-t²/2 dt
Common z-score values:
• z = 1.96 → 97.5th percentile (95% confidence interval)
• z = 2.58 → 99.5th percentile (99% confidence interval)
• z = 1.645 → 95th percentile (90% confidence interval, one-tailed)
This interactive table computes P(Z < z) for z-scores from 0.00 to 3.49 using the error function approximation. The highlighted cell shows the entry closest to your current z-score.