WEIBULL.DIST Function

Basic Description

The Excel WEIBULL.DIST function calculates the Weibull Probability Density Function or the Weibull Cumulative Distribution Function for a supplied set of parameters. Although the function is new in Excel 2010, it is simply a renamed version of the Weibull function, which is available in Excel 2007 and earlier.

Syntax: WEIBULL.DIST( x, alpha, beta, cumulative )

Where the function arguments are:

x The value at which the function is to be calculated (must be ≥ 0)
alpha The Shape parameter to the distribution (must be > 0)
beta The Scale parameter to the distribution (must be > 0)
cumulative A logical argument which denotes the type of distribution to be used;

TRUE = Weibull Cumulative Distribution Function
FALSE = Weibull Probability Density Function

 

Weibull.Dist Function Examples

Example 1 – Weibull Probability Density Function

The chart on the right shows the Weibull Probability Density Function with the shape parameter, α = 3 and the scale parameter, β = 1.

If you want to calculate the value of this function at x = 1, this can be done with the Weibull.Dist function, as follows:

=WEIBULL.DIST( 1, 3, 1, FALSE )

This gives the result 1.10363832351433.

Plot of Weibull Probability Density Function with Alpha=3 and Beta=1Weibull Probability Density Function with α = 3 and β = 1
Example 2 – Weibull Cumulative Distribution Function

The chart on the right shows the the Weibull Cumulative Distribution Function with the shape parameter, α = 5 and the scale parameter, β = 1.5.

If you want to calculate the value of this function at x = 2, this can be done with the Weibull.Dist function, as follows:

=WEIBULL.DIST( 2, 5, 1.5, TRUE )

This gives the result 0.985212776817482.

Plot of Weibull Cumulative Distribution Function with Alpha=5 and Beta=1.5Weibull Cumulative Distribution Function with α = 5 and β = 1.5

 

 

Weibull.Dist Function Errors

If you get an error from the Excel Weibull.Dist function this is likely to be one of the following :

#NUM! Occurs if either the supplied x value is < 0 or the supplied alpha or the supplied beta argument is ≤ 0
#VALUE! Occurs when either of the supplied alpha or beta arguments are non-numeric

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