totn Excel Functions

MS Excel: How to use the RND Function (VBA)

This Excel tutorial explains how to use the Excel RND function with syntax and examples.

Description

The Microsoft Excel RND function returns a random number that is greater than or equal to 0 and less than 1. You can use the RND function in a formula to generate a random number within a range of values.

The RND function is a built-in function in Excel that is categorized as a Math/Trig Function. It can be used as a VBA function (VBA) in Excel. As a VBA function, you can use this function in macro code that is entered through the Microsoft Visual Basic Editor.

Syntax

The syntax for the RND function in Microsoft Excel is:

Rnd ( [number] )

Parameters or Arguments

number
Optional. It specifies what random number to return (see return values below).

Returns

The RND function returns a random number that is greater than or equal to 0 and less than 1.
If the number provided is greater than 0 or the number parameter is omitted, the RND function will return the next random number in the sequence using the previously generated random number as the seed.
If the number is less than 0, the RND function will return a random number using number as the seed.
If the number is 0, the RND function will return the random number that was most recently generated.

Random Integer Range

To create a random integer number between two values (range), you can use the following formula:

Int ((upperbound - lowerbound + 1) * Rnd + lowerbound)

Where lowerbound is the smallest number and upperbound is the largest number that you want to generate a random number for.

Int ((25-10+1) * Rnd + 10)

The formula above would generate an integer random number between 10 and 25.

Applies To

  • Excel for Office 365, Excel 2019, Excel 2016, Excel 2013, Excel 2011 for Mac, Excel 2010, Excel 2007, Excel 2003, Excel XP, Excel 2000

Type of Function

  • VBA function (VBA)

Example (as VBA Function)

The RND function can only be used in VBA code in Microsoft Excel.

Let's look at some Excel RND function examples and explore how to use the RND function in Excel VBA code:

Int ((6 - 1 + 1) * Rnd + 1)
Result: random number between 1 and 6

Int ((200 - 150 + 1) * Rnd + 150)
Result: random number between 150 and 200

Int ((999 - 100 + 1) * Rnd + 100)
Result: random number between 100 and 999

For example:

Dim LRandomNumber As Integer

LRandomNumber = Int ((300 - 200 + 1) * Rnd + 200)

In this example, the variable called LRandomNumber would now contain a random number between 200 and 300.

Add the Randomize function

If you find that you are not getting a truly random number when calling the RND function, you can use the RANDOMIZE function to change the seed value for the RND function's random number generator. The call to the RANDOMIZE function should preceed the call to the RND function.

For example,

'Example provided by techonthenet.com

Sub Macro1

   Dim LRandomNumber As Integer

   Randomize
   LRandomNumber = Int ((300 - 200 + 1) * Rnd + 200)

End Sub

In this example, the variable called LRandomNumber would now contain a random number between 200 and 300. The Randomize function would ensure that the number generated is truly random by initializing the random number generator with a seed value that is equivalent to the system timer.

Warning: If you don't call the Randomize function before calling the Rnd function, the Rnd function may return the same random number value each time. And therefore, you may not get a truly random number.