📊Poisson Distribution Calculator
Enter the average rate (λ) and a value k to find Poisson probabilities.
Free Poisson Distribution Calculator
This Poisson distribution calculator finds the probability of observing exactly k events, at most k events, or at least k events, given an average rate λ — using P(X=k) = (λ^k × e^−λ) / k!. The Poisson distribution models the number of independent events occurring in a fixed interval, given a known average rate.
Common examples include the number of customers arriving per hour, defects per batch, or calls received per minute — anywhere events happen independently at a constant average rate. The bar chart shows the full probability distribution around your value of k.
Free, instant, and runs entirely in your browser — no sign-up required.