# Excel Custom Functions: A Comprehensive Guide For 2023

Wednesday, May 3rd 2023. | Excel Templates

## Introduction

Microsoft Excel is one of the most powerful tools in the business world, used for everything from simple calculations to complex data analysis. One of the most useful features of Excel is its ability to create custom functions. Custom functions allow users to create their own formulas and functions to perform calculations that are not built into Excel. In this article, we will explore the basics of Excel custom functions and provide you with some tips, samples, and frequently asked questions to help you get started.

## What are Excel Custom Functions?

Excel custom functions are user-defined functions that can be created using the Visual Basic for Applications (VBA) programming language. VBA is a programming language that is built into Excel and can be used to create custom macros, automate tasks, and create custom functions. Custom functions can be used just like any other Excel function, but they are tailored to specific tasks or calculations that are not built into Excel.

## Sample Custom Functions

Here are three sample custom functions that you can create in Excel:

### 1. Calculate the Age of a Person

This custom function calculates the age of a person based on their birthdate. To create this function, open the Visual Basic Editor (VBE) by pressing Alt + F11, then insert a new module. In the module, enter the following code: “` Function Age(BirthDate As Date) As Integer Age = DateDiff(“yyyy”, BirthDate, Date) If Date < DateSerial(Year(Date), Month(BirthDate), Day(BirthDate)) Then Age = Age - 1 End Function ``` To use this function, simply enter the formula =Age(A1) into a cell, where A1 is the cell containing the person's birthdate.

### 2. Convert Fahrenheit to Celsius

This custom function converts a temperature from Fahrenheit to Celsius. To create this function, open the VBE and insert a new module. In the module, enter the following code: “` Function FahrenheitToCelsius(Temperature As Double) As Double FahrenheitToCelsius = (Temperature – 32) * 5 / 9 End Function “` To use this function, simply enter the formula =FahrenheitToCelsius(A1) into a cell, where A1 is the cell containing the temperature in Fahrenheit.

### 3. Calculate the Average of a Range, Excluding Zeros

This custom function calculates the average of a range of numbers, excluding any zeros. To create this function, open the VBE and insert a new module. In the module, enter the following code: “` Function AverageNoZeros(Range As Range) As Double Dim Cell As Range, Total As Double, Count As Long For Each Cell In Range If Cell.Value <> 0 Then Total = Total + Cell.Value Count = Count + 1 End If Next Cell If Count = 0 Then AverageNoZeros = 0 Else AverageNoZeros = Total / Count End If End Function “` To use this function, simply enter the formula =AverageNoZeros(A1:A10) into a cell, where A1:A10 is the range of numbers that you want to average.

## Tips for Creating Custom Functions

Here are a few tips to keep in mind when creating custom functions: – Keep your functions simple and focused on specific tasks. – Test your functions thoroughly before using them in important spreadsheets. – Use descriptive names for your functions to make them easy to remember and use. – Make sure your functions handle errors gracefully, such as by returning an error message instead of crashing Excel.

## Frequently Asked Questions

Here are some frequently asked questions about Excel custom functions:

### 1. How do I create a custom function in Excel?

To create a custom function in Excel, open the Visual Basic Editor (VBE) by pressing Alt + F11, then insert a new module. In the module, write your function using the VBA programming language.

### 2. How do I use a custom function in Excel?

To use a custom function in Excel, simply enter the function name and arguments into a cell, just like any other Excel function.

### 3. Can I share my custom functions with others?

Yes, you can share your custom functions with others by saving them in an Excel add-in or by sharing the VBA code with others.

### 4. Can I use VBA to create custom functions in other Office applications?

Yes, you can use VBA to create custom functions in other Office applications, such as Word and PowerPoint.

### 5. Can I create custom functions that work with non-numeric data?

Yes, you can create custom functions that work with non-numeric data, such as text and dates.

### 6. Can I create custom functions that perform complex calculations?

Yes, you can create custom functions that perform complex calculations using the VBA programming language.

### 7. Are there any limitations to using custom functions in Excel?

Custom functions can be slower than built-in Excel functions, so it’s important to keep your functions as efficient as possible. Additionally, some Excel features, such as PivotTables, may not work with custom functions.

## Conclusion

Excel custom functions are a powerful tool for anyone who works with data in Excel. By creating your own custom functions, you can simplify complex calculations and automate repetitive tasks. With the tips, samples, and frequently asked questions provided in this article, you should be well on your way to creating your own custom functions in no time.

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