Free Up Space with macOS Storage Optimization

A full startup volume slows everything: swaps get tight, Time Machine verification crawls, and updates refuse to install. macOS ships with enough storage tooling to fix this yourself in an afternoon, no third-party cleaners needed.

What you need

• About 30 minutes
• Admin access to System Settings
• Ideally a current backup; see [[time-machine-first-backup]] if you have none yet

Step by step

1. Check where space actually went: open System Settings, General, Storage, and wait for the category bars to finish calculating. Guessing wastes effort; the breakdown rarely matches intuition.
2. Empty the biggest low-risk bucket first: Trash, then Downloads sorted by size. Old installers (.dmg and .pkg files) are safe deletions that often free several gigabytes.
3. Review Recommendations on the same Storage screen. Store in iCloud moves photos and files off-device transparently; Empty Bin Automatically deletes trash older than 30 days.
4. Hunt duplicate caches in the developer folders if you code: ~/Library/Caches, old simulators via xcrun simctl delete unavailable, and stale Homebrew downloads with brew cleanup --prune=all.
5. Use Apple's own inspector: in Finder, choose Go to Folder and visit /Library sparingly, but prefer the Storage screen's Documents browse mode, which lists large files across the home folder sorted by size.
6. Compress archives you keep: right-click project folders you rarely touch and choose Compress, then delete the original. Text-heavy projects shrink dramatically.
7. Offload video and photo libraries. Media dominates most drives; move completed projects to an external drive and delete local copies only after confirming the copy plays back.
8. Watch system data growth: local Time Machine snapshots can hold tens of gigabytes. They clear automatically as space runs low, but you can list them with tmutil listlocalsnapshots / and thin them with tmutil thinlocalsnapshots / 999999999999 4.
9. Set a standing rule: act whenever free space drops below 10 percent of the drive. Calendar a monthly five-minute check of the Storage screen rather than waiting for the "your disk is almost full" warning.

Common mistakes

• Running unknown "cleaner" apps that delete shared caches other apps depend on.
• Deleting items inside /System or /Library to chase space; those folders are mostly immutable links and protected volumes anyway.
• Confusing purgeable space with real usage; iCloud-synced and snapshot-held space frees itself when needed.

Related guides

Storage health supports every other workflow here. A clean disk makes [[time-machine-first-backup]] finish faster and keeps [[brew-essentials-install]] caches from ballooning, since runtimes and casks are repeat offenders. Large media libraries you decide to keep local are also easier to navigate once windows are arranged sensibly per [[free-window-management-macos]].