How to Quickly Resize & Crop Images using a Mac

I’ve been a Mac user for many years, but I only learnt this nifty resize and crop trick in the last 12 months. It totally changed my workflow when it come to resizing images for my blog, so I thought I’d put together a quick tutorial for all the other Mac users who aren’t aware they can do this! :)

Note: This will usually make changes to your original files unless you choose duplicate in the menu system instead of save, so be wary of this if you want to keep your original images unchanged.

The first thing you need to do is locate the image(s) you’d like to change. Select them, right click and choose “Open With..Preview.app”

Once you’ve images have opened in Preview hit Cmd+A to select them all if you’re working with multiple images. If you just want to resize/crop one image, go straight to Tools > Adjust Size

From here you can adjust your photos based on a few different options. I tend to set a default width and resolution (72dpi is fine for web but if you’re planning on printing your images you might want to up it to 300dpi or so).

Note: All your images will have the same width/height/dpi depending on which options you set, so bare than in mind when you’re changing your files.

Hit ok and Preview will work its magic on your images. If you don’t want to crop your images you can skip the next step. If you do, use your mouse to select and drag the area that you want to crop (if you want a perfect square you can hold down Shift while you drag)

Once you’ve done that you should see a Crop button in the bottom toolbar. (If you can’t see the bottom toolbar click on the pencil icon, the blue one in the image below). If you still don’t see a crop button, hit the Adjust Size button (the double ended arrow) and cancel the dialog and the crop button should appear after that.

From here you’ll want to save your images, or duplicate if you don’t want to edit your original files. You can either choose File > Save or hit Cmd+S. Duplicate is Cmd+Shift+S.

And that’s it – once you’ve saved your images go back to Finder and you should now see your resized &/or cropped images ready for uploading. I said it was simple, right?!
Preview is great if you want to batch resize a lot of photos but don’t want the hassle of importing them to iPhoto and exporting them again, or having to bother to fire up Photoshop or Lightroom. Once you get the sequence down (which doesn’t take long) you should be able to do this in a minute or less! :)