How to Resize Photos on a Mac: A Step-by-Step Guide

Resizing photos on your Mac is a simple yet valuable skill. Whether you need smaller images for web use or larger ones for a presentation, we’ll walk you through the process step by step. You don’t need to be a tech guru; Mac provides user-friendly tools for this task. Here’s how to resize photos on a Mac effortlessly.

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Before we dive into the step-by-step instructions, let’s take a moment to appreciate the convenience of Preview. It’s not only accessible but also offers a user-friendly interface, making it a great choice for resizing images on a Mac.

Step 1: Open Your Image

  • Locate the image you want to resize on your Mac.
  • Simply double-click on the image file, and it will open in Preview.

Step 2: Access Markup Mode

  • In the Preview window, you’ll find various tools at the top. Look for the “Markup” icon, which resembles a toolbox.
  • Click on the “Markup” icon to access the editing tools, including resizing.

Step 3: Adjust Image Size

  • Once you’re in Markup mode, click on the “Adjust Size” icon.
  • A pop-up window will appear, allowing you to modify the image’s dimensions.
  • You can change the width and height to your desired values.

Step 4: Save Your Resized Image

  • After adjusting the size, click “OK” in the pop-up window.
  • Preview typically saves your edits in the existing file.
  • To keep the original image, go to “File” and select “Export…”
  • Save your changes as a new file with a different name.

Step 5: Batch Resizing (Optional) If you have multiple images to resize, Preview can handle that too.

  • Select all the images you want to resize in a Finder folder.
  • Right-click on the selected images and choose “Open With” > “Preview.”
  • In Preview, select all the thumbnails on the side.
  • Go to “Tools” in the top menu and choose “Adjust Size.”
  • Keep in mind that all images will be saved on top of existing files. If you want to keep the original images, create copies before batch resizing.

Step 6: Additional Tips (Optional) For those seeking further optimization:

  • Consider the right resolution based on your needs (e.g., web or print).
  • Explore different image formats.
  • Learn how to watermark your images for added protection or branding.


Resizing photos on a Mac using Preview is a breeze. We’ve walked you through each step, from opening your image to adjusting its size and saving the changes. Now, it’s your turn to put this knowledge into action. Experiment with resizing your images and enjoy the convenience of Preview on your Mac.