Poisson Distribution Calculator

The average number of events you expect per interval — for example 3 support calls per hour.

A larger λ shifts the distribution to the right and widens it, since both the mean and the variance of a Poisson variable equal λ.

The event count you want probabilities for. The tool reports the chance of exactly, at most, and at least this many events in one interval.

Must be a whole number, e.g. 2 calls in an hour.