# Reducing System Data Storage on macOS "System Data" is the catch-all category Apple's Storage panel uses for everything that isn't cleanly bucketed into Apps, Documents, Photos, etc. — caches, logs, Time Machine local snapshots, VM/swap files, and more. It's notoriously vague and prone to appearing inflated even when nothing is actually wrong. Apple has reportedly improved how it's categorized in macOS Tahoe versus older versions, but the underlying causes below still apply. Healthy range is roughly 12–25GB; worth investigating if it's pushing past 30GB. ## Check current size - macOS Ventura and later: **Apple menu → System Settings → General → Storage**, hover the gray "System Data" bar for the figure - Pre-Ventura: **Apple menu → About This Mac → Storage tab** ## Built-in cleanup tool **Apple menu → About This Mac → More Info → Storage Settings** (or, pre-Ventura, **About This Mac → Storage → Manage**) surfaces Apple's own recommendations — reduce clutter, delete old downloads/backups, empty trash automatically. ## Time Machine local snapshots Local snapshots kept for Time Machine can quietly eat tens of GB. Via Terminal: ``` tmutil listbackups sudo tmutil delete [path to backup] tmutil listlocalsnapshots / tmutil deletelocalsnapshots [snapshot name] ``` To stop this recurring, disable automatic local backups under **System Settings → General → Time Machine**. ## Cache and log files Finder → **Go → Go to Folder**, then check size with Cmd+I before deleting anything inside: - `~/Library/Caches` — app and system caches - `~/Library/Logs` — log files - `~/Library/Application Support` — leftover data from uninstalled apps - `~/Library/Containers` — sandboxed app data, same story - `~/Library/Cookies` These accumulate especially from apps that were deleted without a proper uninstall. ## Screensaver video downloads (Sonoma+) If you use Apple's 4K video screensavers, macOS caches them locally and this can run up to ~20GB, counted as System Data rather than against the screensaver itself. Location: `/Library/Application Support/com.apple.idleassetsd/Customer` ## Spotlight index The Spotlight index can grow large. Rebuilding it is safe but will make Spotlight search temporarily slower while it re-indexes: ``` sudo du -hs /System/Volumes/Data/.Spotlight-V100/ sudo rm -rf /System/Volumes/Data/.Spotlight-V100/ ``` ## iOS device backups **System Settings → General → Storage**, find "iOS Files," select and delete old ones. Or directly at: `~/Library/Application Support/MobileSync/Backup` ## Downloads folder Finder → Downloads, sort by size, clear out anything no longer needed — an easy, low-risk win that's often overlooked. ## Caution Back up (Time Machine or otherwise) before manually deleting anything under `/Library` or `/System`. Don't run Terminal commands from random sites/ads without understanding what they do first — this is one of the more common ways people damage a otherwise-fine install while "cleaning up." --- *Not yet covered here and worth adding if it comes up: developer-specific bloat (Xcode derived data, iOS Simulators, Docker images) and Recovery Mode-level fixes (disk permission repairs, NVRAM resets) — none of the sources checked for this note addressed those directly.*