Using the “Preview” app on a Mac to re-size an image

Near the bottom of the sizing window, you’ll see a line that says 1.1 MB (was 2.8). So before I sized this down, it would not have uploaded to our site. You can simply bring down the WIDTH enough to get that number between 1MB and 2MB. I changed width from 10 inches to 8 inches, and that did the trick.

You’ll learn how to size and edit photos using Adobe Photoshop, but sometimes you just need to quickly size a photo down to put on a website or social media. Preview comes installed on every Mac and offers a quick solution. Check out this article on for instructions.

Our class website will only allow you to upload images that are 2MB or less. To use PREVIEW to size down your photos, first open the image in PREVIEW (on a Mac, Preview is the default image editor — unless the owner has changed that to another app), so simply double clicking the file should open it in Preview.

With the image open, Select Tools > Adjust Size to bring up the Resize dialog, which will allow you to resize the image. It supports many measurement units, including pixels. By default, it will resize the image proportionally, maintaining the original aspect ratio to ensure the resized image doesn’t look stretched.

Remember, you are trying to size down the image so the file size is between 1MB and 2MB. When you are done sizing, save the file with a new name. Pay attention to where you are saving it to so you make sure you upload the new and resized file, not the original.