Why Is Docker Taking So Much Space on Linux

What Causes This?

Docker can use a surprising amount of disk space because it keeps more than just your active containers. Old images, stopped containers, build cache, unused volumes, and leftover networks can all stay on the system unless you remove them manually. On Linux, this data is usually stored under Docker’s data directory, so space usage can grow quickly if you build images often, run many containers, or forget to clean up after tests and updates.

Common Symptoms

• Your Linux drive keeps losing free space even when you are not saving many files
• docker system df shows large usage for images, containers, volumes, or build cache
• You see “no space left on device” errors when building or starting containers
• Docker Desktop or WSL-based Docker storage grows much larger than expected on Windows
• Removing a container does not seem to free much disk space

How to Fix It Manually

1. Check how much space Docker is using.

   • Open Terminal.
   • Run:

     docker system df

   • This shows how much space is being used by images, containers, local volumes, and build cache.

2. Remove stopped containers.

   • Stopped containers still take up space.
   • Run:

     docker container prune

   • Type y to confirm.

3. Delete unused images.

   • Docker often keeps old image layers after updates and rebuilds.
   • Run:

     docker image prune -a

   • This removes images not being used by any container.
   • If you want to review images first, run:

     docker images

4. Clear the build cache.

   • If you build images often, the build cache can become very large.
   • Run:

     docker builder prune

   • To remove all unused build cache, use:

     docker builder prune -a

5. Remove unused volumes.

   • Volumes can hold databases, app data, and other persistent files even after containers are gone.
   • Check existing volumes:

     docker volume ls

   • Remove unused ones:

     docker volume prune

   • Be careful: this can delete data you may still need.

6. Run a full Docker cleanup.

   • If you want Docker to remove most unused data in one command, run:

     docker system prune -a --volumes

   • This removes:
     • stopped containers
     • unused networks
     • unused images
     • unused build cache
     • unused volumes
   • Only use this if you are sure you do not need that data.

7. Check Docker’s storage location if space still looks wrong.

   • On Linux, Docker data is commonly stored in:

     /var/lib/docker

   • To inspect its size, run:

     sudo du -sh /var/lib/docker

   • If it is still huge after cleanup, look for large logs or leftover files inside container directories.

8. If you use Docker Desktop on Windows with Linux containers, check WSL storage too.

   • Open PowerShell and run:

     wsl --list --verbose

   • Docker data may be inside a WSL virtual disk that keeps growing.
   • In that case, cleaning Docker data and temporary files on Windows can also help recover space.

Fix It Automatically with Kudu

If Docker-related cache, temporary files, and leftover container data are filling your drive, Kudu can help find and clean the clutter automatically. It’s a faster option if you do not want to hunt through Docker storage, WSL files, and system junk by hand.

Download Kudu Free →