Normal CDF calculator

Find the probability P(Z ≤ z) — the area under the standard normal curve to the left of z.

z =

Standard normal CDF

Φ(z) = P(Z ≤ z) where Z ~ N(0,1). Common values: Φ(0) = 0.5, Φ(1) = 0.8413, Φ(1.645) = 0.95, Φ(1.96) = 0.975, Φ(2.576) = 0.995.

Confidence levels

90% CI: z = 1.645. 95% CI: z = 1.96. 99% CI: z = 2.576.

Common z-values
P(Z≤0) = 0.5 P(Z≤1) = 0.8413 P(Z≤1.96) = 0.975 P(Z≤−1) P(Z≤2) P(Z≤3)
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Normal PDFZ-scoreNormal distributionConfidence interval