Alternatively, right-click the image, choose Open With, and then Preview. Find the photo you wish to resize in Finder and then double-click to launch it in Preview.This tool comes pre-installed on all macOS computers and can help you polish your images with minimal fuss. Resizing photos on your Mac is as easy as counting 1,2,3 with the free Preview app. How to Resize Photos on Mac Easily and Quickly So, this guide is going to teach you how to resize images professionally on Mac using some free excellent programs. However, learning how to resize photos on Mac using the free Preview app can save you subscription money on top of being simple to use. When it comes to editing images by resizing on desktops, Adobe Photoshop comes to mind. 4.15 10 Easy Way Do Split-Screen on Mac.4.11 Best 12 Alternatives to CleanMyMac.2.7 Use QuickTime to Record Screen on Mac.1.26 Toast Titanium Alternative for Mac.