# Documentation/Calc Functions/POISSON.DIST

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## Function name:

POISSON.DIST

## Category:

Statistical Analysis

## Summary:

Calculates either a probability mass function or a cumulative distribution function of the Poisson distribution for a given value.

## Syntax:

POISSON.DIST(**Number**; **Mean**; **C**)

## Returns:

Returns a real number which is either a probability mass function or a cumulative distribution function of the Poisson distribution for **Number** with mean value as **Mean**.

## Arguments:

**Number** is a real number or a reference to the cell containing that number which represents the value based on which the Poisson distribution is calculated.

**Mean** is a real number or a reference to the cell containing that number which represents the middle value of the Poisson distribution.

**C** can be 0 or False to calculate the probability mass function. It can be any other value or True to calculate the cumulative distribution function.

- If
**Number**is a non-integer value then the function uses its floor value, i.e. it is truncated to an integer. However, if the**Number**is less than 0 then the function returns an error value. - If
**Mean**is less than 0 then the function returns an error value.

## Additional details:

- The formula for POISSON.DIST is:

If **C** is FALSE(), POISSON.DIST returns the probability mass function value:

If **C** is TRUE(), POISSON.DIST returns the cumulative distribution function value:

where x is **Number**

- For more details on Poisson distribution, visit Wikipedia

## Examples:

Formula | Description | Returns |
---|---|---|

=POISSON.DIST(8;4.5;1) | The function calculates the cumulative distribution function for the poisson distribution. | 0.959742687517962 |

=POISSON.DIST(8;4.5;0) | The function calculates the probability mass function for the poisson distribution. | 0.046329159165318 |

=POISSON.DIST(-11.2;4.5;0) | The function returns an error value since the Number is negative. |
Err:502 |

=POISSON.DIST(11.2;-4.5;0) | The function returns an error value since the Mean is negative. |
Err:502 |

## Related LibreOffice functions:

## ODF standard:

None

## Equivalent Excel functions:

POISSON.DIST