How to Quickly Resize Images with a Mac Quick Action

Here’s a quick guide to creating an Automator service (quick action) so that you can quickly resize image files with a simple right-click.

macOS Automator Quick Action Panel Header Image
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There are a bunch of different ways to resize images on Mac. Any image editing app worth its salt will have a resize function as one of its most basic operations. There are online services, where you can upload images, have the online service resize them, and then save them again.

If you’re using a Mac, there’s another option that can be extremely quick and convenient. It takes just a few minutes to set up the first time, but after that, it’s just a right-click away. It’s free, and it doesn’t involve installing any apps or software–it’s already baked into macOS.

It’s also very simple, which makes it easy and quick to use, but it also means you only have limited control over the output. If you need more sophisticated and granular controls, another option will work better (the free app XnConvert might be a good place to start). But if you consistently find yourself downsizing images to specific sizes for email or social media, for example, this can be an extremely effective option.

Using macOS Automator to Resize Images

It uses Mac’s built-in Automator app to create a Quick Action (or what used to be called context menu services) so that you can right-click on the file or files and resize them.

Open the Automator App

You can find it under:

/Applications/Automator.app

Set Type of Action

When it asks you for the type of document, choose Quick Action. (In older versions of Mac OSX, it was called Service.)

Screenshot: Mac Automator Resize Image - Choose Quick Action

Then hit the Choose button.

Set Workflow Options

It will have added an initial section to the workflow area at the right. For the top option next to “Workflow receives current”, select the “image files” option. Leave the rest at their defaults (you can customize the image and color fields if you like, but there’s no need to).

Screenshot - Mac Automator Resize Image - Choose Image Files option

Set Processing Type

From the Library in the left column, click on Photos to narrow the available actions. In the list of actions (second from left), scroll down and choose “Scale Images.” 1

Then right-click and go to Services and choose from the list.

It works on one image file or multiple files. If for some reason you’re mixing image files amongst other files in the same folder, it is possible to add a filter earlier in the workflow so that it only applies to image files. Explore the Filter Finder Items action under Files & Folders in the actions Library panel (far left).

Tip: Add a Keyboard Shortcut

You can also apply keyboard shortcuts to your Quick Actions. To do that, go to:

Automator > Services > Services Preferences

Then, find the service on the list and click on it. You’ll see a small “Shortcut” button appear to the right of the name. When you click on the Shortcut button, you’ll get a field where you can just press the keyboard combination you want to use for it.

macOS Automator Service Add Keyboard Shortcut

Just be sure to avoid other global shortcut combinations–there’s no warning message if you step on an existing shortcut’s toes–it just won’t work as expected.

Things Worth Knowing

When you run this action, it’s going to replace and overwrite the existing files. So make sure you’re working on disposable copies, not the originals.

Automator is baked into macOS, so there’s no need to install anything and buy anything.

The app you’ve just created is available immediately. There’s no need to restart the computer or Finder.

If you choose the pixel dimension option, it refers to the longest side, whether that’s in landscape (horizontal) or portrait (vertical) orientation.

If you run this on images that are smaller than your output dimensions, it will resize larger. But it won’t magically restore detail that was already lost when making the smaller image.

While I’ve only outlined a very basic Quick Action here, it’s quite possible to expand on this workflow and add other actions and operations into the workflow sequence. For instance, you could combine it with converting the image type or some other manipulation or action that’s available in Automator.

What is macOS Automator?

Automator is a tool that’s baked right into macOS. It doesn’t receive a lot of attention, but it’s really, really handy to have. You can find it under:

/Applications/Automator.app

Basically, automaton gives you visual tools in the form of building blocks to build workflows. So you can accomplish a bunch of useful tasks without writing any code (although you can add Applescript code, if you need something more customized).

Even better, quite a few Mac apps add actions and tools to Automator that extend the power and functionality of Automator. This usually happens automatically in the background when you install the app. An example is Photoshop–it will add a bunch of new actions that are useful for tweaking and manipulating images.

Even better, some Mac apps add actions and tools to Automator that extend the power and functionality of Automator. This usually happens automatically in the background when you install the app. Sadly, an excellent collection of Automator tools to interact with Photoshop that was put out by Ben Long no longer works with current versions of macOS (although Photoshop has its own separate toolkit for creating Photoshop actions which can be incredibly powerful but work differently from Automator actions).

Where Automator excels is in saving time and adding convenience with time-consuming, repetitive tasks such as this. But it can also be surprisingly powerful if you want it to be.

  1. You might notice that in the screenshot I have several other Scale Images and Resize Image options on the list. These are third-party actions that have been added by various imaging apps on my Mac. They would also work, but for the purposes of this guide, I’m focusing on the one that’s included by default as part of Automator without installing anything else.)

    Click and then drag to the right-hand workflow panel.

    Screenshot - Mac Automator Resize Image - Set Processing Type

    Set Image Resizing Options

    There are two options you can set. The first is whether to resize to a specific pixel dimension or to scale by percentage. In most cases, the pixel dimension option is probably most useful. With that, it’s not going to matter what size the incoming image is–it will output a consistent image size out. But there are also situations where the percentage option might be useful.

    The second is the value, whether percentage or dimensions. In this example, I’m setting it to 1200 pixels. It’s important to note here that you only have control over one dimension; in this case, it’s referring to the longest side. So whether the image is in landscape (horizontal) or portrait (vertical) orientation, it will make the longest side to this pixel dimension.

    Optional Tweak

    If you’re always resizing to the same dimensions, you can leave it as is. But you can also tweak it to let you input the dimension each time you run it.

    To do that, click on Options in the Scale Images panel. And then check the box that says ‘Show this action when the workflow runs.”

    Screenshot: macOS Automator Scale Images Show this Action When the Workflow Runs

    Then, when you run the action later, you’ll get a popup similar to this panel where you can change the dimension on the fly.

    Screenshot: macOS Automator Resize Images Quick Action Scale Images Popup

    Overwriting Originals vs New Output Files

    The workflow will work as it currently stands, but it will overwrite the original files. If you’re always working with disposable copies in their own folder, you can go ahead and export the action as is.

    But you can also tweak it so that the output consists of entirely new files and leaves the originals as is.

    Here’s a simple way to do this by adding Duplicate Finder Items and Rename Finder Items actions into the workflow sequence:

    macOS Automator Resize Images with Duplicate Files

    You can extend it even further if you like by creating a new output folder and then moving the new files into that, and so on.

    Export Automator Quick Action

    That’s all you need to do with the workflow section. Now you just have to export it as an action.

    In Automator’s main menu, go to File > Export.

    Export Automator Action

    In the Export As section, name it to whatever you like. Something like Resize to 1200px seems like a logical choice for this particular action. Then choose where you want to save it. This is only a temporary spot for it, so it makes sense to put it somewhere you’ll find it quickly, like the Desktop. Then click the Save button.

    Install Automator Quick Action

    Next, find the file you just saved using Finder or, if you put it on the Desktop, just go to the Desktop. Double-click on the file.

    You’ll get a popup asking if you want to install it as a quick action (or service).

    Screenshot - Mac Automator Resize Image - Quick Action Installer

    Click on the Install button. The .workflow version will then be automatically moved, and you can now use right-click in Finder to convert the file using the quick action.

    Using Your New Quick Action

    The app you’ve just created is available immediately. There’s no need to restart the computer or Finder.

    To use it, select the image or images in Finder or your preferred Mac file browser (I use Forklift; Commander One is another popular option). ((If you’re specified Finder in the top panel where it says “Service Receives Selected…”, then use Finder for this. :) []

David Coleman / Photographer
by David Coleman

I'm a professional freelance travel photographer based in Washington DC. Seven continents, up mountains, underwater, and a bunch of places in between. My images have appeared in numerous publications, and you can check out some of my travel photography here. More »

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