Docker Desktop is using tens of GB on your Mac: how to reclaim it

Docker Desktop stores everything inside a single virtual disk image, so it shows up as one huge chunk of System Data. Deleting files inside containers doesn’t always shrink it, which is why the number surprises people.

See what is using the space

docker system df

This splits usage into images, containers, local volumes and build cache, and shows how much of each is reclaimable.

Remove what is unused

docker system prune

Removes stopped containers, unused networks, dangling images and build cache. It asks before it runs. Adding -a also removes every image not used by a container, which means re-downloading them later.

Adding --volumes deletes unused volumes, and that is where database data lives. Check docker volume ls first; deleted volumes can’t be recovered.

If the disk image stays large

After pruning, the image file may not shrink immediately. In Docker Desktop, Settings → Resources lets you lower the disk image limit, and the app’s Troubleshoot menu has a reset option that clears all data, so use it only if you can lose everything inside Docker.

Docker is one of several large System Data contributors. This checklist covers the rest.

Disclosure: this guide is published by the developer of McCleaner. Scanning is free; cleaning is paid, from €1.99. Back up important data before deleting anything. Commands are provided as is.