Docker Tip #44: Show Total Disk Space Used by Docker
Here's a simple command to show you much disk space is being taken up by Docker images, containers, volumes and build cache.
Docker has a system sub-command that has a few useful commands. One of them is docker system df which reports back disk space usage stats of your Docker installation.
Here’s what the output of docker system df looks like on my machine:
| TYPE | TOTAL | ACTIVE | SIZE | RECLAIMABLE |
| Images | 212 | 0 | 63.72GB | 63.72GB (100%) |
| Containers | 0 | 0 | 0B | 0B |
| Local Volumes | 77 | 0 | 1.01GB | 1.01GB (100%) |
| Build Cache | 0 | 0 | 0B | 0B |
This is on a machine with dozens of real world Dockerized projects that are mostly Flask, Rails, Phoenix and NodeJS apps spanning across multiple versions.
My build cache is empty because I run docker system prune as a daily scheduled task. If you want to see how to set that up on any OS, check out Docker Tip #32.
You can pry even deeper by using the -v flag (verbose). It will show you the unique image size for each image. You’d be surprised at how small some of them are!
What does your df output look like? Let me know in the comments below.