Custom functions for Google Sheets using Apps Script

As someone who frequently works with Google Sheets, I've found that custom functions are very useful for automating repetitive tasks.

What Are Custom Functions?

While Google Sheets offers powerful built-in functions like SUM, AVERAGE, and COUNT, you can extend its capabilities by writing your own functions using Apps Script. These are called custom functions. Once you create these functions, you can use them in your spreadsheet formulas just like native functions.

Prerequisites

This tutorial assumes that you are familiar with the following concepts:

Writing your first custom function

Let's start with a simple example: creating a function that returns your lucky number. While this may seem basic, it introduces key concepts we'll build upon. Before coding, let's outline a few details:

  • Purpose: Return a predetermined lucky number

  • Function Name: Pick a descriptive name (eg. MYLUCKYNUMBER)

  • Input Parameters: None required

  • Output: A numerical value (your lucky number).

I think the number 3 brings me luck so here is a function that returns my lucky number.

function MYLUCKYNUMBER () {
   return 3;
}

Here is a screenshot of the above function in the Apps Script editor.

Screenshot of the Google Apps Script code editor.

You can now use this custom function in a Google Sheets formula just like any other function.

Screenshot of a Google Sheets spreadsheet.

You should see your lucky number displayed in the cell where you entered the formula.

Screenshot of a Google Sheets spreadsheet.

Learn more

You can learn more about custom functions in Google Sheets by reading the following tutorials:

The following tutorials are examples of custom functions that you can create:

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