Enhancing Google Sheets with Custom Formulas and Functions

Google Sheets is an incredibly powerful tool for data analysis and collaboration. One of its most robust features is the ability to create custom functions using Google Apps Script, which can be used just like any built-in function within your spreadsheets. This capability allows you to tailor Google Sheets to your specific needs, making data manipulation and analysis even more powerful. In this blog post, we will delve into how to create custom functions that manipulate and return values based on the content of the cells they reference.

Understanding Custom Functions in Google Sheets

Custom functions in Google Apps Script let you extend the functionality of Google Sheets beyond its standard feature set. These functions can read the content of cells passed as arguments and perform operations based on those values, much like standard spreadsheet functions.

Basic Principles of Custom Functions

  • No Side Effects: Custom functions should not change the state of the spreadsheet. They can’t set values or format cells (i.e., they are not supposed to have side effects).
  • Deterministic: Ideally, for the same inputs, a custom function should always produce the same output.
  • Accessibility: Custom functions can be used by anyone with access to the spreadsheet, just like regular functions.

Creating a Custom Function to Process Cell Data

Let’s create a basic custom function that takes the value of an existing cell, performs an operation, and returns a new value. For this example, we’ll write a function that squares the number given to it.

Step 1: Open the Script Editor

  1. Open your Google Sheets document.
  2. Click on Extensions > Apps Script.
  3. Delete any code in the script editor and rename your project.

Step 2: Write the Custom Function

In the script editor, enter the following function:

* Squares the input value.
* @param {number} input The value to square.
* @return The square of the input value.
* @customfunction
function SQUARE(input) {
if (typeof input !== 'number') {
throw 'Input must be a number';
return input * input;


  • Function Definition: The function SQUARE takes one parameter input.
  • Error Handling: Checks if the input is a number. If not, it throws an error.
  • Processing: Returns the square of the input.

Step 3: Save and Use the Function in Your Spreadsheet

  1. Click the disk icon to save your script.
  2. Close the Apps Script tab and return to your spreadsheet.
  3. In any cell, use the formula =SQUARE(A1) (assuming A1 contains a numeric value).

Extending Functionality

You can extend this basic principle to create more complex functions. For instance, you might want to write a function that accepts a range of cells, processes each cell’s value, and returns an array of new values.

Example: Summing Squares of a Range

* Calculates the sum of squares of the values in the given range.
* @param {range} range A range of cells to process.
* @return The sum of squares of the values.
* @customfunction
function SUMOFSQUARES(range) {
var sum = 0;
range.forEach(function(row) {
row.forEach(function(cell) {
if (typeof cell === 'number') {
sum += cell * cell;
return sum;


  • In your sheet, input =SUMOFSQUARES(A1:B2) to sum the squares of values in the range A1 to B2.


Custom functions in Google Apps Script offer a powerful way to extend the capabilities of Google Sheets. By creating functions tailored to specific needs, you can enhance your data manipulation and analysis tasks, making your workflows more efficient and your data more insightful. Whether you are performing simple calculations or handling complex data processing tasks, custom functions can significantly improve your experience with Google Sheets.