To keep both your original image and the resized (or otherwise edited) one, go to File > Export… and save your changes as a new file. Note that by default, Preview saves all edits in the existing file. In the pop-up window, set your desired image dimensions and click OK: In the Markup mode, click Adjust Size icon:.Find Markup icon in the top menu bar of the Preview window (for narrow images, the icon often hides behind the >.Open an image in Preview (simply double-click on the file to open it and Preview is the default option in most cases).If you go to Finder > Applications and scroll through the apps, you’ll find Preview, an image viewing and editing app that comes with your Mac. Macs actually have a built-in image editing software that can resize images on your Mac.
