Excel VBA provides two procedures. One is **functions** also known as the **user-defined functions** another one is **subroutines. **In this tutorial, I am going to discuss how to use the Excel VBA user-defined function in the Excel formula.

The Excel VBA user-defined function is a process that is written in VBA which accepts some inputs & in return gives a result when the function is called.

This article is part of my series: Excel VBA & Macros – A Step by Step Complete Guide.

## Example of an Excel VBA User-Defined Function

Before entering into details, at first, I introduce you to the method Speak(). This method has the following syntax:

expression.Speak (Text, [SpeakAsync], [SpeakXML], [Purge])

The **expression** represents a **Speech** object.

Though **Speak()** method can take three arguments, but **Text** argument is the required one, the rest are optional. I shall use **Speak()** function by passing only the **Text** argument. So, in this case, it is a function of one argument. This method uses an Excel **text-to-speech generator** to “speak” the text passed to it through **Text** argument.

Function SpeakTheText(text) Application.Speech.Speak (text) End Function

**Note: **To hear the voice, your system must be set up to play sound.

## Using VBA function in excel cell

For example, if you want to use the **SpeakTheText()** function to hear the content of cell A1, you have to use the following formula:

=SpeakTheText(A1)

You can use this function in a slightly more complex formula, as shown below. In this example, the argument is a text string (**“Good achievement”**) rather than a cell reference.

=IF(SUM(A:A)&gt;1000, SpeakTheText("Goal achievement"),)

The above formula calculates the sum of the values in Column A. When that sum exceeds 1,000, you will hear **“Good achievement”**.

When you use the **SpeakTheText** function in a worksheet formula, the function always returns **0**, because this function is returning nothing. In another word, I can say, there is no value assigned to the function’s name (**SpeakTheText**) variable.

*Read More: An Excel VBA function with a range argument*

## Another Example of Excel VBA User-Defined Function

Okay, now I’m going to deal with a more complex function. This function is designed for a sales manager who calculates the monthly commission that he has to pay to his salespersons. To boost up the sales of the company, the commission rate structure is based on the amount sold— those who will sell more will earn a higher commission rate.

The function takes the sales amount through the only argument (Sales) and returns the commission earned by a salesperson. The function will calculate the commission according to the following table:

### Table: Monthly Sales Target & Commission Rates

Monthly Sales | Commission Rate |
---|---|

0-$9,999 | 8.0% |

$10,000-$19,999 | 10.5% |

$20,000-$39,999 | 12.0% |

$40,000+ | 14.0% |

You can use more than one method to calculate commissions for various sales amounts.

### Using Nested IF function

Assume that you have the sales amount for a particular salesperson in a worksheet cell A4. Now you can use the following formula:

= IF (AND (A4>=0, A4<=9999.99), A4*0.08, IF (AND (A4>=10000, A4<=19999.99), A4*0.105, IF (AND (A4>=20000, A4<=39999.99), A4*0.12, IF (A4>=40000, A4*0.14, 0))))

This approach isn’t a good solution for the following reasons:

**Firstly**, the formula is undoubtedly complex and not easy to understand.**Secondly**, the commission rates are hard-coded into the formula. If the commission structure changes in the future, it would be tough and toilsome to modify the formula.

### Using VLOOKUP function

A simple and better solution is using a VLOOKUP table. I have entered the data of the above table (Monthly Sales Target & Commission Rates) in cell range G8: H11. Click this link to know about VLOOKUP function, if you don’t know.

**Note: **It is important to note that I have used 0 for the data range 0-9999, 10,000 for 10,000-19,999, 20,0000 for 20,000-39,999 and 40,000 for 40,000+. When I do so, Excel searches data < 10,000 in 0 row, 10,000 ≤ data ≤ 19,999 in 10,000 row, 20,000 ≤ data ≤ 39,999 in row 20,000 and data ≥ 40,000 in row 40,000.

=VLOOKUP(A4, $G$8: $H$11, 2)*A4

Use this function in other cells to calculate the sales commission earned by the sales force.

## Using VBA Function in Excel Formula

Like the following one, you can create a custom function to calculate the commission earning by the sales force.

Function CommissionEarning(Sales) 'Calculates sales commissions Rate1 = 0.08 Rate2 = 0.105 Rate3 = 0.12 Rate4 = 0.14 Select Case Sales Case 0 To 9999.99 CommissionEarning = Sales * Rate1 Case 10000 To 19999.99 CommissionEarning = Sales * Rate2 Case 20000 To 39999.99 CommissionEarning = Sales * Rate3 Case Is &gt;= 40000 CommissionEarning = Sales * Rate4 End Select End Function

I have used the custom function in cell D4 using the argument A4, as A4 holds the sales. Then I have copied this function for other cells. The figure below shows this:

Download commission-calculation.xlsm to work with yourself

Happy Excelling ☕