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Below you will find descriptions and links to 5 free statistics calculators for computing values associated with the Poisson distribution.

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This calculator will compute the cumulative distribution function (CDF) for the Poisson distribution, given the number of event occurrences and the expected number of event occurrences.

This calculator will compute cumulative probabilities for a Poisson outcome, given the total number of events observed, the expected number of events per interval, and the total number of intervals. For the total number of events observed *k*, the calculator will return P(K<k), P(K≤k), P(K>k), and P(K≥k).

This calculator will compute the exact 99%, 95%, and 90% confidence intervals for a Poisson mean, given the number of event occurrences.

This calculator will compute a Poisson probability (i.e., the probability of a specific number of events occurring within a specific number of fixed intervals of time or space), given the total number of events observed, the expected number of events per interval, and the total number of intervals.

This calculator will compute the probability mass function (PMF) for the Poisson distribution, given the number of event occurrences and the expected number of event occurrences.