Normal Distribution: P(Z ≤ 1.0)
P(Z ≤ 1.0) = 0.8413, meaning approximately 84.1% of data in a normal distribution falls below one standard deviation above the mean.
How to use this tool
- Enter z-score in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your p(z ≤ z) — cumulative probability and the full breakdown beneath it.
Calculate the cumulative normal distribution probability for z = 1.0, one of the most commonly referenced points on the bell curve.
Frequently asked questions
- What does Φ(z) represent?
- Φ(z) is the cumulative distribution function of the standard normal distribution — the probability that a standard normal random variable is less than or equal to z. For example, Φ(1.96) ≈ 0.975, corresponding to the 95% confidence interval.