Probability—
As a percentage—
Step by step
Enter a mean and standard deviation to find the probability that a normal variable falls below, above or between values — with the area shaded on the bell curve.
Step by step
Enter the mean and standard deviation, choose a probability type, and read the area under the curve.
Type the mean (μ) and standard deviation (σ) of your normal distribution.
Pick P(X < x) for a left tail, P(X > x) for a right tail, or P(a < X < b) for a range, and enter the value(s).
The probability equals the shaded area under the bell curve. It is shown as a decimal and a percentage, with the z-score in the steps.