# EXPONDIST function

Returns the exponential distribution. Use EXPONDIST to model the time between events, such as how long an automated bank teller takes to deliver cash. For example, you can use EXPONDIST to determine the probability that the process takes at most 1 minute.

Important   This function has been replaced with one or more new functions that may provide improved accuracy and whose names better reflect their usage. Although this function is still available for backward compatibility, you should consider using the new functions from now on, because this function may not be available in future versions of Excel.

## Syntax

`EXPONDIST(x,lambda,cumulative)`

The EXPONDIST function syntax has the following arguments (argument: A value that provides information to an action, an event, a method, a property, a function, or a procedure.):

• X     Required. The value of the function.
• Lambda     Required. The parameter value.
• Cumulative     Required. A logical value that indicates which form of the exponential function to provide. If cumulative is TRUE, EXPONDIST returns the cumulative distribution function; if FALSE, it returns the probability density function.

## Remarks

• If x or lambda is nonnumeric, EXPONDIST returns the #VALUE! error value.
• If x < 0, EXPONDIST returns the #NUM! error value.
• If lambda ≤ 0, EXPONDIST returns the #NUM! error value.
• The equation for the probability density function is:

• The equation for the cumulative distribution function is:

## Example

The example may be easier to understand if you copy it to a blank worksheet.

1. Select the example in this article. If you are copying the example in Excel Online, copy and paste one cell at a time.
Important: Do not select the row or column headers.

Selecting an example from Help

1. Press CTRL+C.
2. Create a blank workbook or worksheet.
3. In the worksheet, select cell A1, and press CTRL+V. If you are working in Excel Online, repeat copying and pasting for each cell in the example.
Important: For the example to work properly, you must paste it into cell A1 of the worksheet.
4. To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.

After you copy the example to a blank worksheet, you can adapt it to suit your needs.

A B
Data Description
0.2 Value of the function
10 Parameter value
Formula Description (Result)
=EXPONDIST(A2,A3,TRUE) Cumulative exponential distribution function (0.864665)
=EXPONDIST(0.2,10,FALSE) Probability exponential distribution function (1.353353)

Applies to:
Excel 2010