WEIBULL function
Returns the Weibull distribution. Use this distribution in reliability analysis, such as calculating a device's mean time to failure.
Important This function has been replaced with one or more new functions that may provide improved accuracy and whose names better reflect their usage. This function is still available for compatibility with earlier versions of Excel. However, if backward compatibility is not required, you should consider using the new functions from now on, because they more accurately describe their functionality.
For more information about the new function, see WEIBULL.DIST function.
Syntax
WEIBULL(x,alpha,beta,cumulative)
The WEIBULL function syntax has the following arguments:

X Required. The value at which to evaluate the function.

Alpha Required. A parameter to the distribution.

Beta Required. A parameter to the distribution.

Cumulative Required. Determines the form of the function.
Remarks

If x, alpha, or beta is nonnumeric, WEIBULL returns the #VALUE! error value.

If x < 0, WEIBULL returns the #NUM! error value.

If alpha ≤ 0 or if beta ≤ 0, WEIBULL returns the #NUM! error value.

The equation for the Weibull cumulative distribution function is:

The equation for the Weibull probability density function is:

When alpha = 1, WEIBULL returns the exponential distribution with:
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.
Important Do not select the row or column headers.
Selecting an example from Help

Press CTRL+C.

In Excel, create a blank workbook or worksheet.

In the worksheet, select cell A1, and press CTRL+V.
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.

