LOGNORM.DIST Function

Basic Description

The Excel LOGNORM.DIST function calculates the Log-Normal Probability Density Function or the Cumulative Log-Normal Distribution Function for a supplied value of x. The Lognorm.Dist function is new in Excel 2010 and so is not available in earlier versions of Excel. However, the function is simply a new version of the Lognormdist function that is available in earlier versions of Excel.

Syntax: LOGNORM.DIST( x, mean, standard_dev, cumulative )

Where the function arguments are listed in the following table:

x The value at which you want to evaluate the log-normal distribution function
mean The arithmetic mean of ln(x)
standard_dev The standard deviation of ln(x)
cumulative A logical argument which denotes the type of distribution to be used:

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


Lognorm.Dist Function Example

Example 1 – Normal Probability Density Function

The chart on the right shows the the Log-Normal Probability Density Function for a variable, x. The mean of ln(x) is 10 and the Standard Deviation of ln(x) is 5.

If you want to calculate the value of this function at x = 0.5, this can be done using the Excel Lognorm.Dist function, as follows:

=LOGNORM.DIST( 0.5, 10, 5, FALSE )

This gives the result 0.016210482.

Plot of Log-Normal Cumulative Distribution Function with Mean=10 and Standard Deviation=5Log-Normal Probability Density Function with mean ln(x) = 10 & std. dev. ln(x) = 5
Example 2 – Cumulative Log-Normal Distribution Function

The chart on the right shows the the Log-Normal Cumulative Distribution Function for a variable x. Again, the mean of ln(x) is 10 and the Standard Deviation of ln(x) is 5.

If you want to calculate the value of this function at x = 12, this can be done using the Excel Lognorm.Dist function, as follows:

=LOGNORM.DIST( 12, 10, 5, TRUE )

This gives the result 0.066417115.

Plot of Log-Normal Cumulative Distribution Function with Mean=10 and Standard Deviation=5Log-Normal Cumulative Distribution with mean ln(x) = 10 & std. dev. ln(x) = 5

 

Lognormdist Function Errors

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

#NUM! Occurs if the supplied x ≤ 0 or the supplied standard_dev ≤ 0
#VALUE! Occurs if any of the supplied arguments are non-numeric

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