Running out of disk space on a Mac slows everything — swap files grow, Time Machine snapshots multiply, and apps fail to save. Apple’s built-in Storage overview (System Settings → General → Storage) is a starting point, but it often labels tens of gigabytes as “System Data” without explaining which subfolder is responsible. Developers, creative professionals, and AI tool users frequently discover that a single cache directory or Docker image store accounts for more space than all their Documents combined.
This guide walks through free built-in methods, Terminal techniques, and visual analysis with AI Agent Clean’s Space Lens disk analyzer — all compatible with macOS 14 Sonoma and later.
Start with macOS Storage settings
- Open System Settings → General → Storage.
- Wait for the usage bar to finish calculating — large drives can take a minute.
- Review categories: Applications, Documents, iCloud Drive, macOS, System Data.
- Click i icons or “…” menus where available to empty Trash, remove watched media, or review large files.
Storage settings are safe but coarse. “System Data” bundles caches, local snapshots, VM swap, and ~/Library junk — you need deeper tools to act on it.
Terminal: du and find (advanced)
Power users run disk usage commands:
du -sh ~/* | sort -hr | head -20— top-level home folder sizes.du -sh ~/Library/* | sort -hr | head -20— Library breakdown (may need FDA for all paths).find ~ -size +1G -print 2>/dev/null— files over 1 GB (slow on large drives).
Terminal is precise but slow to interpret and easy to misread when mount points or firmlinks redirect paths on modern macOS volumes.
Space Lens treemap workflow
Space Lens renders a squarified treemap: each rectangle is a file or folder sized by bytes. Click to drill down, double-click to open in Finder, and spot multi-gigabyte surprises visually.
- Launch AI Agent Clean → Space Lens.
- Choose a volume — internal SSD or external drive (grant Removable Volumes access if prompted on macOS 14+).
- Start at
/or~depending on whether you suspect system or user data. - Drill into large rectangles — common culprits:
Library/Application Support,Developer/Xcode, Docker, VM images. - Jump to cleanup modules when ready — Smart Scan, AI Agent Clean, or Large Files.
Space Lens analysis runs locally — no cloud upload of your file tree. See Privacy Policy.
- Finding space is read-only; deleting requires separate careful steps.
- Do not delete files in /System or /usr without expert knowledge.
- External drives may sleep — wake them before scanning.
- Full Disk Access improves scan completeness for third-party analyzers.
- Compare findings with System Data too large before bulk cleanup.
Common space hogs on macOS 14+
- Time Machine local snapshots — can consume dozens of GB until thinned.
- Xcode DerivedData — rebuildable build artifacts.
- AI tool caches — Cursor, Claude, Codex; see our Cursor guide.
- iOS backups — ~/Library/Application Support/MobileSync/Backup.
- Mail downloads — especially with large attachments.
- Duplicate media — use Duplicates module after Space Lens identifies clusters.
Maintenance habits
Schedule a monthly Space Lens pass, empty Trash after cleanup, and keep at least 15% free space for APFS efficiency and swap. Pair visualization with Smart Scan for actionable cleanup categories rather than ad-hoc deletes.
External drives and network volumes
Space Lens supports removable volumes when macOS grants access. External SSDs used for photo libraries or Time Machine often hide duplicate “Archive” trees — drill into rectangles labeled Backups.backupdb or vendor-specific sync folders before deleting from the internal drive only.
Network mounts (SMB, NAS) scan slowly; start with local volumes for interactive exploration, then schedule overnight scans on mounted shares if needed.
Built-in Large Files in Storage
macOS 14 Storage sometimes lists “Large Files” separately — useful for quick wins but without treemap context. Cross-check those paths in Space Lens to see sibling folders you might miss in a flat list. AI Agent Clean’s Large & Old Files module sorts items over 50 MB with last-access dates for action after visualization.