Excel WEIBULL function

The Excel WEIBULL function calculates the Weibull distribution. This is a legacy function that was replaced by the WEIBULL.DIST function in Excel 2010. Although WEIBULL is still available for backward compatibility, Microsoft recommends using WEIBULL.DIST for new work, as it provides better accuracy and consistency with other modern statistical functions. For a detailed explanation of the Weibull distribution and practical examples, see the WEIBULL.DIST function.

Purpose

Get the PDF or CDF of the Weibull distribution.

Return value

A number representing the probability density or cumulative probability value.

Syntax

=WEIBULL(x,alpha,beta,cumulative)

x - The value at which to evaluate the distribution (must be ≥ 0).
alpha - The shape parameter of the distribution (must be > 0).
beta - The scale parameter of the distribution (must be > 0).
cumulative - A logical value that determines the form of the function. If TRUE, returns the cumulative distribution function; if FALSE, returns the probability density function.

Using the WEIBULL function

The WEIBULL function calculates values for the Weibull distribution, which is a continuous probability distribution commonly used to model the time until failure of a component or system. The Weibull distribution is particularly useful in reliability engineering, survival analysis, and failure time analysis, as it can model increasing, constant, or decreasing failure rates depending on the value of the shape parameter (alpha).

For better accuracy and consistency with other modern statistical functions, it is recommended to use the WEIBULL.DIST function. WEIBULL.DIST uses the same arguments and provides the same core functionality with improved numerical precision. See the WEIBULL.DIST function for more details.

Notes

WEIBULL is a legacy function. For Excel 2010 and later, use the WEIBULL.DIST function.
If any argument is non-numeric, WEIBULL returns the #VALUE! error.
If x < 0, WEIBULL returns the #NUM! error.
If alpha ≤ 0 or beta ≤ 0, WEIBULL returns the #NUM! error.