How to resize a batch of images on a Mac with Automator

There are many instances when you may need to resize images. Large 16 Megapixel images from your camera are great for prints, but overkill for posting online. They take a while to upload, may not fit into email attachment limits, and are scaled down on the web anyways. This quick guide will show you got to use the built-in Apple Automator application to resize batches of images. It’s quick, easy, and free.

Automator is an application that first appeared in Mac OS X 10.4 (Tiger). It is used for recording workflows and automating repetitive tasks, saving users time and effort. Once you familiarize yourself with automator, it can be used for some fairly complex actions.

The following steps will show you how to make an Automator workflow that you can save on your Desktop or in your Applications folder. You can drag and drop batches of images directly on it, and it will output the resized images in a folder on your desktop. You only need to follow these steps once to create a workflow, and you can resize as many images as you like later.

  1. Open Automator. It’s in your Applications folder.
  2. You are greeted with the Automator start screen, select Application for type on document.
  3. Automator editor opens and you are presented with the interface.
    In the left panel you have the categories of actions, such as Calendar, Contacts, Developer, etc… In the center panel you see the available actions from the category. Under Files & Folder find the New Folder action, and drag it to the editor on the right.
  4. Enter a name and location for your new folder. This will be your output folder.
  5. Now, drag the Get Folder Contents action into the editor.
  6. Under the Photos category, find the Scale Images action and drag it into the editor.
  7. You will be prompted to add a Copy Finder Items action. We don’t need to make a copy because we’re making a new folder, and we will be dragging images onto the workflow. Select Don’t Add.
  8. Enter the desired width of your resized images. We’re using 640 pixels in this example. You may also use percentages.
  9. At this point you’ve made a basic image resize workflow. Save you workflow to begin using it. Click on File menu, select Save, or press Command key + S.
    Give it a descriptive name, save it where ever you want it. On the Desktop for example. Make sure to save it as an Application.
  10. Now you built a small automator “app” that takes images as input, and creates a folder on your desktop with resized output! Drag images on to the icon, and watch the output appear almost instantly.

  11. You’re done! And you can save your app for the future, and create any number of new ones specific to different tasks.

If you explore the different actions available you will realize just how powerful this software is. Resize, crop, rotate, rename, print, etc…

This guide was written for OS X 10.8 Mountain Lion with Automator 2.3. But the steps should be similar on earlier versions as well.

More great mac tips:

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  • Kyle

    Thanks, mate, that helped. With a different actions order, but nevertheless. Cheers!

  • Eric Silva

    Brilliant! Exactly what I was looking for.

  • J. Paul

    I used Automator for photo-resizing. but if you need more options or features, Automator is not the first choice.

    I recommand Sizerox.

    This app offers many features and can resize, rename or watermark in batch mode.
    There is a demo if you want to try the app.

  • Wes Craft

    Unfortunately in OS 10.7.5 with Automator 2.2.4 batches of larger than about 180 images don’t seem to complete. They’ll stall out during resizing as far as I can tell. There’s no running status so I can’t tell what’s going on with it but I need this to work on 1200 photos at a time all nested in subfolders. My tests worked but I had 1 folder with three subfolders of 10 images each. Everything worked like a charm and quickly but running it with 7 folders and 150 or so images in each folder did not work. I check Activity monitor to see what was going on and it showed 0.03% of the CPU was being used on my Automator created App. Any thoughts?

  • M!ke

    Nice! Still works on 10.10.2

    One change: I did include a ‘Copy Finder Items action’ in the application. Oddly, that’s where the ‘output’ images appeared. The actual ‘output’ folder just got copies of the original images.

    Thanks for the clear instructions, roman!

  • Jason

    exactly what I was looking for – thanks so much for the simple step by step instructions.