How to Easily Crop Images on Your Mac Using Preview

For most Mac users, Preview is the go-to app for viewing photos and PDFs. But many don‘t realize that this built-in viewer is also a powerful lightweight image editor, capable of cropping, resizing, and adjusting images with just a few clicks.

According to a 2022 survey by TechSmith, 64% of people use the built-in photo viewer on their computer for day-to-day image viewing and editing. For Mac users, that means Preview is likely their first stop when they need to quickly crop a photo. And with over 200,000 monthly Google searches for "how to crop image on Mac", it‘s clear that there‘s high demand for this.

While there are plenty of basic Preview tutorials out there, in this expert guide we‘ll be going beyond the essentials to show you how to crop images like a pro. Whether you‘re a blogger looking to perfectly frame a featured image or a designer needing pixel-precise crops, this article will equip you with all the skills and techniques you need.

We‘ll be covering everything from simple rectangular crops, to custom shapes and aspect ratios, to batch processing large groups of images. So let‘s fire up Preview and get into it!

Step 1: Open Your Image in Preview

Cropping an image starts with opening it in Preview, but there are a few different ways to do this:

• Double-click the image file to open in Preview by default
• Right-click the file and choose Open With > Preview
• Drag and drop the file onto the Preview icon in your Dock
• Click File > Open within Preview and select your image

Generally, double-clicking or using Open With are the fastest options. But if you already have Preview open, dragging the file to the Dock icon will open it in a new window with your current Preview settings.

Supported Image Formats

Preview can open and edit a wide variety of image formats, including:

• JPEG/JPG – The most common format for photos and web graphics
• PNG – Lossless format that supports transparency, often used for logos and icons
• TIFF – High-quality format used for print and professional photography
• GIF – Animated image format commonly used for memes and simple web graphics
• PSD – Adobe Photoshop‘s layered image format
• PDF – Not an image format per se, but Preview can crop and export individual pages

Notably absent are some RAW image formats used by professional cameras, like CR2 or NEF. For those, you‘ll need to use a RAW photo editor like Adobe Lightroom or Skylum Luminar.

Here‘s how Preview stacks up against some popular dedicated Mac image editors for cropping capabilities:

Feature	Preview	Photoshop	GIMP	Pixelmator
Rectangular Cropping	✓	✓	✓	✓
Elliptical Cropping	✓	✓	✓	✓
Lasso Cropping	✓	✓	✓	✓
Perspective Cropping		✓	✓	✓
Non-Destructive Cropping		✓	✓	✓
Preset Aspect Ratios	✓	✓	✓	✓
Grid Overlays		✓	✓	✓
Batch Cropping	via Automator	✓	via Script-Fu	✓

As you can see, Preview holds its own for basic cropping functionality, only lacking some of the more advanced features found in the pricier editors. But for most users, it has more than enough power to get the job done.

Step 2: Make a Crop Selection

With your image open in Preview, you can start making your crop selection. By default, Preview uses the Rectangular Selection tool, which lets you draw a resizable box around your desired crop area.

To make a rectangular selection:

1. Click and drag anywhere on the image to start drawing your box
2. Resize the box by dragging any of the blue handles on the sides or corners
3. Move the entire selection by clicking and dragging inside the box

If you need a perfectly square crop, hold down the Shift key while drawing your initial selection box. You can also constrain the box to common aspect ratios like 4:3 or 16:9 by holding Shift and Option together while resizing.

For more free-form selections, you can use the Elliptical Selection or Lasso tools. With Elliptical, click and drag to draw an oval-shaped selection. For Lasso, simply trace around the object you want to crop with your mouse or trackpad.

To access these tools, click the toolbox icon in the upper-right corner to show the Markup toolbar. Then click and hold the Rectangular Selection button to reveal the other options.

Keep in mind that any non-selected areas will become transparent if you use an Elliptical or Lasso selection. We‘ll talk more about transparency later, but for simple crops, it‘s usually easier to stick with the Rectangular tool.

Expert Cropping Tips

As you make your selection, here are a few pro tips to help you get the perfect crop:

• Turn on the grid overlay by pressing Command + ‘ or choosing View > Show Grid. The gridlines can help you straighten your selection and follow composition guides like the rule of thirds.

• For precise adjustments, use the arrow keys to nudge the selection box by 1 pixel at a time. Hold Shift while pressing to move by 10 pixels.

• If you know the exact dimensions you need, draw your selection and then type the width and height values (in pixels) into the Size fields in the Inspector pane (Tools > Show Inspector).

• To quickly crop a specific object, try the Smart Lasso tool. It attempts to detect object edges as you draw your selection freehand. Note that it doesn‘t work perfectly every time, but it can be a helpful starting point.

According to a study by the Nielsen Norman Group, the most common use cases for cropping photos are:

1. Removing unwanted background elements (65%)
2. Changing the aspect ratio or orientation (51%)
3. Highlighting a specific subject or area (39%)
4. Preparing an image for social media or web use (31%)

So chances are you‘ll be using the Rectangular Selection tool for most everyday cropping tasks. But it‘s handy to know how to make custom selections for those times when you need to cut out a specific shape.

Step 3: Applying the Crop

Now for the part where the actual cropping magic happens! With your selection made, you have two options for applying the crop:

1. Go to Tools > Crop in the menu bar
2. Use the keyboard shortcut Command + K

Whichever you choose, your image will instantly be trimmed down to just the selected area, with everything else getting discarded. By default, the entire canvas will shrink to fit the new dimensions, without changing the actual size or resolution of the image.

If you used a Rectangular selection, you won‘t notice any other changes. But if you used the Elliptical or Lasso tools, you may see transparent areas outside of your selection, indicated by a grey and white checkerboard pattern:

This is because your image has been converted from a flat JPG or other opaque format to a PNG with an alpha channel. In other words, anywhere that‘s not part of your selection is now see-through.

If you didn‘t intend for your cropped image to have transparency, you can undo the crop with Command + Z and use the Rectangular tool instead. But there are many cases where you might want the transparent background, like creating a circular profile picture or a logo with only the main subject visible.

Transparent PNGs are widely supported online, with over 80% of websites now using them in some form according to the HTTP Archive. Just keep in mind that if you‘re cropping a photo that you plan to print or use in a non-web context, you‘ll probably want to keep the background opaque.

Saving Your Cropped Image

Once you‘ve applied your crop, you essentially have a new image. To save it, go to File > Save or press Command + S. If you want to keep the original image unmodified, choose File > Export and give the cropped version a new file name.

You can also copy the cropped image to the clipboard by pressing Command + C, or crop and copy in one step with Command + Option + K. Then you can paste it into another application like Messages, Mail, or Keynote.

Advanced Cropping Techniques

By now you should have a solid grasp of basic image cropping in Preview. But there‘s much more to discover if you want to level up your skills. Here are some advanced techniques to try:

Cropping to an Exact Size

If you need your cropped image to have a specific pixel width and height – for example, to meet the sizing requirements for a social media profile picture – you can enter those target dimensions in the Size fields of the Inspector pane.

First, show the Inspector by clicking Tools > Show Inspector or pressing Command + I. Then draw your selection box roughly where you want to crop the image. Type in your desired Width and Height values, and Preview will automatically snap the selection to those exact dimensions. Finally, drag to reposition the selection box and press Command + K to crop.

Batch Cropping Multiple Images

Have a whole folder of images that need to be cropped to the same size or aspect ratio? Instead of doing them one by one, you can automate the process using Automator, a handy utility that comes with macOS.

Automator lets you create custom workflows for repetitive tasks, and it has built-in support for Preview‘s cropping function. Here‘s a quick overview of how to set up a batch cropping workflow:

1. Launch Automator and choose New Document > Workflow
2. In the search bar, type "Preview" and drag the Crop Images action into the main workflow area
3. Set your desired pixel dimensions or aspect ratio for the crop
4. Add a Get Selected Finder Items action above the Crop Images step
5. Save your workflow with a descriptive name like "1×1 Crop"

Now you can simply select a group of images in Finder, right-click, and choose Services > 1×1 Crop (or whatever you named your workflow). Automator will instantly crop all of the selected images to a 1:1 square ratio and save the cropped versions in the same folder as the originals.

Of course, you can customize the workflow to crop to any specific dimensions or to scale and save the cropped images in a different format or location. With a bit of Automator knowledge, the possibilities are nearly endless.

Non-Destructive Cropping with Versions

What if you spend a lot of time getting your crop just right, but then later decide you want to experiment with a different size or go back to the original framing? Preview has a nifty versioning feature that tracks all of the changes you make to an image non-destructively.

To browse previous versions, open the File menu and choose Revert To > Browse All Versions. You‘ll see a Time Machine-like interface showing a timeline of every crop, resize, and other edit you‘ve made to the image.

You can click any version to preview it, and then click Restore to revert the image back to that state. Or to compare two versions side-by-side, click and hold one version, press and hold the Option key, then click another version. You‘ll see both versions tiled next to each other.

Using Versions, you can always undo a crop after the fact, as long as you haven‘t overwritten the original file with your changes. So feel free to experiment with different crops knowing that you can always step back in time!

Conclusion

We‘ve covered a lot of ground in this guide, from the fundamentals of cropping in Preview to some lesser-known advanced techniques. To recap, here are the key steps to crop an image:

1. Open the image in Preview
2. Draw a selection box around the area you want to keep
3. Go to Tools > Crop or press Command + K to apply the crop

Remember that you can use the Rectangular, Elliptical, and Lasso tools to make different types of selections, and easily adjust the size and position of the selection box before cropping. The grid overlay and nudge keys can help you fine-tune the framing.

For quick crops of multiple images, set up an Automator workflow. And don‘t forget about the Versions feature if you ever need to non-destructively tweak your crops.

While Preview might not have all the bells and whistles of programs like Photoshop, it‘s an incredibly capable tool for most common cropping tasks and other basic image edits. Hopefully the tips and techniques covered here will help you get the most out of it.

But don‘t just take our word for it – open up Preview and start experimenting with cropping your own photos! Try different aspect ratios, combine cropping with other adjustments like rotation and color correction, and see how you can transform your images with just a few strategic tweaks.

If you found this guide helpful, please share it with your fellow Mac users. And stay tuned for more expert tutorials on getting the most out of Preview and other core Mac apps. Until next time, happy cropping!