Clean Up Homebrew Safely

Homebrew manages old versions and cached downloads more actively than it once did. Unless automatic cleanup is disabled, installs and upgrades clean the formulae they touch, and Homebrew periodically cleans all formulae. A long-lived installation can still accumulate downloads, pinned versions, build artifacts, and dependencies. Inspect Homebrew's own metadata before deleting anything under its prefix.

What Homebrew keeps around

Three kinds of leftovers build up:

• Old versions. Cleanup normally removes superseded versions, but retained or recently upgraded versions may remain in the Cellar for a time.
• Downloaded archives. Every bottle and cask download is cached in Homebrew's cache, kept to avoid another download.
• Unused dependencies. Current Homebrew cleanup and uninstall operations normally remove formulae that are no longer needed, unless automatic removal is disabled. Older installations or interrupted operations can still leave some behind.

See the download cache size directly:

brew --cache
du -sh "$(brew --cache)" 2>/dev/null

Cleaning it up

The main command removes old versions and prunes the download cache in one step:

brew cleanup

The current Homebrew manual says ordinary cleanup removes old installed versions and downloads older than 120 days by default. HOMEBREW_CLEANUP_MAX_AGE_DAYS can change that window. Use -n for a dry run. The deeper -s mode scrubs more cached downloads while retaining downloads for currently installed formulae and casks:

brew cleanup -n
brew cleanup -s

Homebrew cleanup and uninstall now remove unused formula dependencies by default. brew autoremove remains useful when you want to inspect that dependency decision directly:

brew autoremove --dry-run
brew autoremove

brew list shows installed packages and brew outdated shows pending updates. Use brew --cellar, brew --caskroom, and brew --cache to discover paths instead of hardcoding /opt/homebrew; Intel and Apple silicon installations differ.

Safe by design

Homebrew cleanup is lower risk than deleting Cellar directories by hand because it uses version and dependency metadata. It can still remove a rollback version or a cached bottle you expected to use offline. Preview both cleanup and autoremove, and keep pinned or operationally critical versions intentionally.

Under the hood: the Cellar, the Caskroom, and how cleanup decides

Homebrew installs each formula into a versioned directory in the Cellar reported by brew --cellar, then links the active version into its prefix. Upgrading places the new version alongside the old before repointing the symlinks. Casks keep versioned metadata under the Caskroom while their app bundles commonly live in /Applications. Downloads use the path reported by brew --cache and are retained according to Homebrew's policy. brew cleanup uses installed-version, retention, and dependency metadata rather than simply deleting every non-current directory. brew autoremove exposes the dependency-only part as a separate command. Because both act on Homebrew's own records rather than guessing, they are safer and more explainable than manual folder removal. A preview is still useful on machines that depend on old toolchains or offline bottles.

Where another tool should stop

A disk map or cleaner can reveal the Homebrew cache and show its size. Mole can surface that category, but Homebrew's own commands remain authoritative for Cellar versions and dependency relationships. Discovery and ownership should not be confused.

A safe order of operations

Use Homebrew's path commands to measure its stores, preview brew cleanup -n, and run ordinary cleanup before considering -s. Preview brew autoremove separately because it answers a dependency question, not a cache question. There is no need for a fixed cleanup schedule when automatic cleanup is working and disk pressure is low.