How to Create a Custom Automator Quick Action to Resize Images in macOS

If you manage a website, create presentations, or frequently email photographs, you know the frustration of dealing with massive 15-Megabyte image files. Modern cameras capture an incredible amount of detail, but uploading a 4K image to a simple blog post will destroy your page loading speeds.

Most users solve this by opening the image in Preview, clicking “Adjust Size,” typing in a new resolution, saving the file, and then repeating that tedious process for every single photo. If you need to resize 50 images, this can take hours.

macOS includes a hidden visual programming app called Automator. You can use Automator to build a custom “Quick Action.” Once built, you can simply right-click on any batch of images, select your new custom action, and the Mac will instantly resize all of them in a fraction of a second. This guide explains how to build it.

Step 1: Open Automator and Create the Workflow

Automator has been part of macOS for over a decade. It allows you to snap together pre-built commands like Lego bricks to create powerful scripts without writing any code.

1. Open the Applications folder on your Mac, or press Command + Spacebar to open Spotlight and search for Automator.
2. When Automator opens, it will ask you to choose a type for your document. Select Quick Action (on older versions of macOS, this is called “Service”).
3. Click the Choose button.
4. Look at the top of the workflow panel on the right. Set the drop-down menu for Workflow receives current to image files.
5. Leave the in drop-down set to Finder.

Step 2: Add the “Scale Images” Action

Now we must tell the workflow exactly what to do when it receives those image files.

1. Look at the library column on the far left. Click on Photos.
2. In the second column, find the action titled Scale Images.
3. Click and drag “Scale Images” into the large grey workflow area on the right side of the screen.
4. A warning box will pop up asking if you want to add a “Copy Finder Items” action so that your original images are not permanently altered. Click Add. This is highly recommended so you do not accidentally destroy your original high-resolution photos.
5. The workflow area will now have two actions stacked on top of each other. The first action (Copy Finder Items) dictates where the resized copies will be saved. By default, it says “Desktop”. You can leave this, or change it to a specific folder.
6. Look at the second action (Scale Images). Type in the maximum width you want your images to be. A good standard for web use is 1200 pixels.

Step 3: Save and Use Your New Tool

Your custom application is now completely finished.

1. Go to the File menu at the top of the screen and click Save.
2. Give your Quick Action a descriptive name, such as “Resize to 1200px”. Click Save.
3. You can now close the Automator app completely.

To test your new tool:

1. Open the Finder and locate some large images.
2. Highlight all of them with your mouse.
3. Right-click on the highlighted images.
4. At the very bottom of the right-click menu, look for Quick Actions.
5. Hover over Quick Actions, and you will see your brand new “Resize to 1200px” button. Click it.

macOS will instantly copy all the highlighted images to your Desktop and aggressively scale them down to your exact specifications, saving you hours of tedious manual formatting.