Quickstart: Custom function

You can use Google Apps Script to write a custom function, then use it in Google Sheets just like a built-in function.

The below quickstart sample creates a custom function that calculates the sale price of discounted items. The sale price is formatted as US dollars.

Set it up

New editor

  1. Create a new spreadsheet.
  2. From within your new spreadsheet, select the menu item Extensions > Apps Script.
  3. Delete any code in the script editor and paste in the code below.
/**
 * Calculates the sale price of a value at a given discount.
 * The sale price is formatted as US dollars.
 *
 * @param {number} input The value to discount.
 * @param {number} input The discount to apply, such as .5 or 50%.
 * @return The sale price formatted as USD.
 * @customfunction
 */
function salePrice(input, discount) {
  let price = input - (input * discount);
  let dollarUS = Intl.NumberFormat("en-US", {
    style: "currency",
    currency: "USD",
});
  return dollarUS.format(price);
}
  1. At the top, click Save .

Legacy editor

  1. Create a new spreadsheet.
  2. From within your new spreadsheet, select the menu item Extensions > Apps Script.
  3. Delete any code in the script editor and paste in the code below.
/**
 * Calculates the sale price of a value at a given discount.
 * The sale price is formatted as US dollars.
 *
 * @param {number} input The value to discount.
 * @param {number} input The discount to apply, such as .5 or 50%.
 * @return The sale price formatted as USD.
 * @customfunction
 */
function salePrice(input, discount) {
  let price = input - (input * discount);
  let dollarUS = Intl.NumberFormat("en-US", {
    style: "currency",
    currency: "USD",
});
  return dollarUS.format(price);
}
  1. Select the menu item File > Save. Name your new script and click OK.

Try it out

  1. Switch back to your spreadsheet.
  2. In a cell, enter =salePrice(100,.2). The first parameter represents the original price and the second parameter represents the discount percentage.

The function results in a sale price of $80.00.

To continue learning about how to extend Google Sheets with Apps Script, take a look at the following resources: