Remove Image Sizes Globally

Every time an image is uploaded or imported, WordPress generates a resized copy for every registered image size. That’s thumbnail, medium and large to start with, plus every extra size your theme and plugins register. It’s not unusual for a single upload to spawn eight or ten resized files. On a large import that’s an enormous amount of CPU and disk work, and a lot of it goes into sizes you may never actually display anywhere on the site.

On the Imports tab you’ll find the "Remove Image Sizes Globally" option. It lets you choose which image sizes to keep, and stops WordPress generating the rest. Instead of blindly producing every registered size, WordPress only produces the ones you’ve told it you want.

The saving shows up in two places. During imports and uploads you’re doing far less CPU work, because there are fewer resizes to generate, so bulk imports run quicker. And on disk you’re storing fewer files, which matters when you’re dealing with tens of thousands of images.

One important point: this option only acts on the sizes you configure. Nothing is removed and nothing is skipped until you’ve gone in and chosen what to keep. That’s deliberate, so you don’t accidentally lose a size your theme relies on. Take a moment to work out which sizes your site genuinely displays, keep those, and let the rest go.

In short: WordPress generates a resized copy for every registered image size, whether you use it or not. On image-heavy imports and uploads that’s a waste of CPU and storage. Remove Image Sizes Globally, on the Imports tab, lets you keep the sizes you need and stop generating the ones you don’t.