Is there a way to determine the size of a docker volume on my macOS machine?

The first step of Federkun's answer worked for me and it returned something like this:

/var/lib/docker/volumes/f4678f...b87/_data

But when I tried

du -sh $(docker volume inspect --format '{{ .Mountpoint }}' volumeNameHere)

it returned a

du: /var/lib/docker/volumes/f4678f...b87/_data: No such file or directory

It turns out Docker works differently on macOS. According to this answer, before I can run the du -sh command I must first screen into the docker virtual machine used by MacOS. You can do so by running

sudo screen ~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/tty

and then you can run

du -sh /var/lib/docker/volumes/f4678f...

to finally get the volume size.

You can use:

docker system df -v

More info at https://docs.docker.com/engine/reference/commandline/system_df/

Building on Federkun's answer:

docker run --rm -v /:/vm-root alpine du -sH /vm-root/$(docker volume inspect --format '{{ .Mountpoint }}' volumeNameHere)

This:

docker volume inspect --format '{{ .Mountpoint }}' volumeNameHere

will return the mount point of the volume on your host. So, to get the size, it's just a matter of doing:

du -sh $(docker volume inspect --format '{{ .Mountpoint }}' volumeNameHere)