Poisson Probability Calculator
Calculate probability of events occurring in a fixed time period
About this calculator
The Poisson Probability Calculator determines the likelihood of specific events occurring within a fixed time period or interval. This statistical tool is essential for analyzing rare events with known average occurrence rates, such as customer arrivals, equipment failures, or phone calls per hour. It's widely used in business forecasting, quality control, telecommunications, and risk assessment to make data-driven decisions and predict future outcomes based on historical patterns.
How to use
Enter the average number of events (lambda) that typically occur in your time period and the exact number of events you want to calculate the probability for. Click calculate to get the Poisson probability result. The calculator will show both the exact probability and percentage format for easy interpretation.
Frequently asked questions
What is the Poisson distribution used for?
The Poisson distribution models rare events occurring independently over fixed time intervals, like customer arrivals, defects in manufacturing, or website visits per minute.
What does lambda represent in Poisson probability?
Lambda (λ) represents the average rate of occurrence - the expected number of events happening in the specified time period or interval.
When should I use Poisson instead of normal distribution?
Use Poisson for rare events with low probability but many opportunities to occur, especially when events are independent and random.