Returns the exponential distribution. Use EXPON.DIST to model the time between events, such as how long an automated bank teller takes to deliver cash. For example, you can use EXPON.DIST to determine the probability that the process takes at most 1 minute.
Syntax
EXPON.DIST(x,lambda,cumulative)
The EXPON.DIST 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, EXPON.DIST returns the cumulative distribution function; if FALSE, it returns the probability density function.
Remarks
 If x or lambda is nonnumeric, EXPON.DIST returns the #VALUE! error value.
 If x < 0, EXPON.DIST returns the #NUM! error value.
 If lambda ≤ 0, EXPON.DIST 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.
How do I copy an example?
 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
 Press CTRL+C.
 Create a blank workbook or worksheet.
 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.
 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) 
=EXPON.DIST(A2,A3,TRUE) 
Cumulative exponential distribution function (0.864665) 
=EXPON.DIST(0.2,10,FALSE) 
Probability exponential distribution function (1.353353) 
