How to Easily Resize Images on a Mac

Resizing images is a common task that every Mac user will need to do at some point. Whether you need to shrink a large photo to send as an email attachment or enlarge a small image for printing, macOS offers several quick and easy ways to resize images to any dimensions you need.

In this comprehensive guide, I’ll explain the basics of image resolution and sizing, when you may need to resize photos and graphics on a Mac, and provide simple step-by-step instructions using built-in Apple tools like Preview, Photos, Safari, and more.

Let’s get started learning the ins and outs of resizing images on your Mac!

Image Resolution Basics

Before learning how to resize, it helps to understand some fundamentals about image resolution.

Resolution refers to the amount of detail an image contains based on its pixel dimensions Resolution is measured in pixels per inch (PPI) or pixels per centimeter

Image size is the actual dimensions of an image – usually defined by width and height in pixels.

A high resolution image has more pixels so it can be enlarged without losing quality. A low resolution image has fewer pixels so quality degrades if you increase its display size.

Matching image resolution to your intended use is important. Web images only need 72 PPI. Print projects require a minimum of 300 PPI for best results. Using images with resolution lower than needed often produces blurry, pixelated results.

When resizing images on your Mac, the goal is to scale the image proportionally so you don’t distort it. Let’s look at when you may need to resize photos or graphics and the tools you can use.

Common Scenarios for Resizing Images on Mac

Here are some of the most common situations where you’ll need to adjust image sizing on a Mac:

• Reducing image size for email – Most email services limit attachment sizes to around 10MB. Resizing large images to lower resolution reduces file size to allow attaching.

• Sharing photos on social media – Facebook, Instagram, Twitter, and other social platforms have specific image dimensions for displaying content properly on different devices. Resizing to the recommended dimensions ensures your images look their best.

• Printing photos – Digital cameras produce photos at 72-300 PPI usually. Resizing to at least 300 PPI creates high quality prints without pixelation or blurring.

• Enlarging small images – Icons, logos, and other graphics may need to be enlarged for print materials, presentations, websites, etc. Resizing increases pixels to allow enlarging small images cleanly.

• Creating thumbnails – Displaying full-size images on web pages consumes bandwidth and slows loading. Generating smaller thumbnails improves performance while linking full images for viewing.

• Cropping to focus on key areas – Cropping images maintains size but removes outer edges to hone in on important portions.

• Fitting images to specific dimensions – Design layouts, templates, and projects often require images to be within defined width/height parameters. Resizing makes images fit as needed.

Now let’s go over your various options for resizing images using the default tools included in macOS and common Mac apps.

How to Resize Images Using Preview

Preview is the default image viewer included on every Mac. It provides a quick and easy way to resize one or multiple images at a time.

To resize an image in Preview:

1. Right click the image file in Finder and choose Open With > Preview. Or double click to open.

2. Select the Adjust Size option from the toolbar.

3. Change the image dimensions by entering specific pixels or percentages.

4. Click OK to resize the image as specified.

5. Choose Export from the File menu to save your resized version as a new file.

Preview also lets you resize by dragging handles on the image borders to scale larger or smaller. And you can choose scaling options like Fit to Window and Actual Size.

Resizing Images in Photos App

The Photos app included on modern macOS versions has great image editing capabilities. Here are the steps for resizing in Photos:

1. Double click a photo to open it.

2. Click Edit in the top right.

3. Select the Crop & Rotate icon.

4. Enter new dimensions or drag handles to scale the image.

5. Click Done and Save to apply resizing.

Photos app makes it easy to resize one or multiple images quickly. Like Preview, it also handles batch exports well.

Resizing Web Images in Safari

Need to grab an image from a webpage and resize it for use elsewhere? Safari makes it simple:

1. Right click the image on the web page and choose Save Image As.

2. In the Save dialog box, click More Options.

3. Adjust sizing, file format, and naming options in the expanded dialog.

4. Click Save to download the resized image file to your Mac.

Safari’s export tool works great for capturing and resizing images from the web.

Using Automator for Batch Resizing

For bulk image processing, Automator is a handy Mac tool that can resize entire batches:

1. Open Automator and select Service as the document type.

2. Add a Watch Me Do action. Then drag in the Scale Images preset.

3. Record resizing steps you want applied to all images.

4. Save and name your new service.

5. Right click image files in Finder and select your new service to process.

Automator is powerful for streamlining repetitive image resizing tasks.

Resize Images in Apple Photos, Pages, and Other Apps

Most Apple apps like Photos, Pages, Keynote, TextEdit, Mail, and more have integrated image resizing capabilities:

• Photos – Select image(s) and click Export to resize dimensions and file format on export.

• Pages, Keynote – Insert image, then adjust size using handles or measurements fields in the inspector pane.

• Mail – When attaching images, select an image and resize dimensions/quality in the attachment options window.

• Preview – Open an image, then choose Tools > Adjust Size and enter new values or scale with handles.

Spend some time exploring the image adjustment capabilities built into your favorite Apple apps. The options allow resizing images directly within many applications.

Use Automator Services for Right-Click Resizing

For quick access to image resizing from Finder, create your own Automator Services.

1. In Automator, select a Service and add Resize Images and Watermark Image actions.

2. Set Resize Images to your preferred dimensions and quality.

3. Save the Service and it will appear in your Finder right-click menu.

Now you can rapidly resize folders of images without opening any other apps!

Resize Images with Apple Shortcuts

The Shortcuts app lets you create custom automations for common tasks. Build one to resize images:

1. Create a new Shortcut and add a Select Photos action.

2. Use Set Variable actions to define new width and height.

3. Add a Resize Image action using the width/height variables.

4. Finish with a Quick Look action to preview resized images.

5. Run your shortcut by selecting images and tapping the Play button.

With Shortcuts, you can resize on demand or set it up to run automatically on newly added photos.

Resize Images on Your iPhone or iPad

If you need to resize images on your iPhone or iPad, it’s just as easy thanks to built-in tools:

• Camera/Photos – After taking a photo, tap Edit and use the Crop tool to set new aspect ratio and size.

• Preview – Open the image in Preview and use the Adjust Size options to scale larger or smaller.

• Apps – Open the image in an app like Pages, Keynote, or Numbers. Use the format panel to resize.

Many of the same methods for resizing images on a Mac also work on iPhone and iPad thanks to Apple’s unified ecosystem.

Use Third-Party Mac Apps for Advanced Resizing

While built-in tools are great for basic resizing needs, third-party Mac apps provide more advanced features:

• ImageOptim – Optimize and compress image file sizes along with resizing.

• GraphicConverter – Batch resize plus filters, color correction, metadata editing, and more.

• Acorn Image Editor – Powerful layer-based editing with precision resize options.

• Affinity Photo – Robust photo editing and graphics app with pro-level tools.

For heavy or specialized image manipulation, dedicated apps like these offer more control over the resize process.

Hopefully this guide gave you a thorough overview of the options for resizing images on your Mac!

The key takeaways are:

• Understand image resolution to pick appropriate sizes.

• Use Preview and Photos for quick individual image resizing.

• Leverage Automator and Shortcuts for efficient batch processing.