How to free up Docker disk space on a Mac

Docker on a Mac runs inside a small Linux virtual machine, and every image, container, volume and build cache lives in that machine's disk image. Deleting files in Finder won't shrink it. Docker's own commands will, as long as you know which ones touch your data.

Where Docker Desktop keeps its disk

Docker Desktop stores everything in one file:

~/Library/Containers/com.docker.docker/Data/vms/0/data/Docker.raw

It's a sparse file. Its stated size is the most it may grow to (the disk usage limit in Docker's settings), while the space it really takes is often much less. Finder and ls show the stated size, which is why Docker.raw so often looks huge. To see what it really uses:

cd ~/Library/Containers/com.docker.docker/Data/vms/0/data
ls -lh Docker.raw   # the size it may grow to
du -h Docker.raw    # the space it takes on your disk

Don't delete or move Docker.raw to save space. It holds every image, container and volume, including databases and anything else you've only stored in Docker. Use the commands below, or Docker Desktop's reset options, instead.

See what's using the space

With Docker running:

docker system df
docker system df -v   # every image, container, volume and cache entry

The summary has four rows: images, containers, local volumes and build cache, each with a "Reclaimable" column. That column is a good guide to what the prune commands below will free. Build cache is often the largest after a few months of docker build.

What each prune command removes

Command	Removes	Risk
`docker builder prune`	Dangling build cache. Add `--all` for all unused build cache.	Low. The next build is slower.
`docker image prune`	Dangling images (untagged layers left by rebuilds). Add `--all` for every image no container uses.	Low. Removed images are pulled or built again.
`docker container prune`	Stopped containers.	Files written inside a container, outside a volume, go with it.
`docker system prune`	Stopped containers, unused networks, dangling images and unused build cache.	As above.
`docker system prune --all`	The same, plus every image no container uses.	You'll pull or build images again.
`docker system prune --volumes`	The same, plus unused anonymous volumes.	Data in those volumes is gone.
`docker volume prune --all`	Every volume no container uses, named ones included.	High: this is where databases keep their data.

Each command lists what it's about to do and asks before it removes anything, unless you add -f. Nothing goes to the Trash.

A safe order to work in

Start with what rebuilds itself:

docker builder prune --all
docker image prune

To keep recent cache and only clear the old, filter by age:

docker builder prune --all --filter until=168h   # older than a week

Then stopped containers and images you no longer use. Check docker ps -a first: a stopped container may be one you meant to start again, with changes inside it that aren't in any image.

docker ps -a
docker system prune --all

Be careful with volumes

Volumes are where containers keep data meant to outlive them: Postgres and MySQL data directories, uploaded files, caches you might want back. A volume counts as "unused" whenever no container is attached to it, including when you've just run docker compose down and plan to bring the project up again tomorrow.

docker volume ls
docker volume ls --filter dangling=true   # volumes no container uses

Since Docker Engine 23, docker system prune --volumes and plain docker volume prune only remove anonymous volumes (the ones with long random names). Named volumes, such as myapp_pgdata, are only removed by docker volume prune --all or docker volume rm. Remove volumes by name when you're sure, rather than in bulk:

docker volume rm old-project_pgdata

If a volume holds the only copy of a database you care about, dump it first (for example with pg_dump run inside the container) and keep the dump outside Docker.

Docker Desktop's own settings

Two things in Docker Desktop are worth knowing:

Disk usage limit. In Settings, under Resources and then Advanced, you can set the most the disk image may grow to. Lowering it can mean Docker has to delete images to fit, so check what you'd lose first.
Clean / Purge data. In the Troubleshoot screen (the bug icon), this deletes all of Docker's data: every image, container and volume. It's the right tool when you want to start again from nothing, and the wrong one otherwise.

After pruning, du on Docker.raw should drop, though it can take a minute for Docker to hand the freed blocks back to macOS.

Colima and OrbStack

Other ways of running Docker on a Mac keep their disks elsewhere, but the same docker prune commands work against them, because they talk to the engine inside the virtual machine.

Colima keeps each machine in ~/.colima/_lima, with the container data disk in ~/.colima/_lima/_disks. colima prune clears only Colima's downloaded assets, not your containers. colima delete removes the whole machine and its settings, and colima delete --data removes the container data too.
OrbStack keeps its data in a disk image inside ~/Library/Group Containers (a folder whose name ends in dev.orbstack), with settings in ~/.orbstack. Use docker commands, or OrbStack's own settings, rather than touching those files.

How ElfClean does it

ElfClean doesn't clean Docker's disk image. It belongs to another app's protected container, and removing it would delete every container and volume at once, so ElfClean only measures it. On the AI & coding screen, "Docker and virtual machine storage" lets you choose Docker.raw or another virtual machine disk and shows the space it takes on disk next to the most it may grow to, with a link to Docker's cleanup instructions.

The same screen has a "Reclaim with the tool's own command" section, which lists docker system prune for Docker, Colima and OrbStack, explains what it removes and that volumes stay unless you add --volumes, and has a button to copy it. ElfClean never runs these commands itself; you paste them into Terminal.

What it does clean are the caches around your projects, such as package downloads and build folders in projects you haven't touched for a while. Those go to the Trash, and History can put them back.