Symptoms
- Storage almost full alert appears
- About This Mac > Storage shows 'System Data' or 'Other' taking up a large amount of space
- Apps and files don't add up to the total space actually used
- Mac feels sluggish when storage is nearly full
Likely causes
- CommonAccumulated caches from apps, browsers, and macOS itselfThese build up over months without automatic full clearing.
- CommonOld Time Machine local snapshots taking up spacemacOS keeps local backup snapshots that can use significant space until cleared.
- PossibleLarge hidden files like iOS device backups or old installer filesThese are easy to forget about and can be several gigabytes each.
- PossibleLog files and diagnostic reports accumulating over timeCrash reports and logs add up slowly but steadily.
- PossibleDownloads and Desktop clutter counted separately from what you'd expectMany people forget how much has piled up in these two folders specifically.
What to do
- Open About This Mac > Storage > Manage to see Apple's built-in breakdown and recommendations.
- Use 'Optimize Storage' options like automatically emptying the Trash after 30 days.
- Check the Documents and Downloads categories for large files you no longer need.
- Delete old iOS backups if you don't need them, found under Manage > iOS Files or in Finder's device backups.
- Restart the Mac, since local Time Machine snapshots and some caches clear automatically over time and after a reboot.
- Empty the Trash fully if you haven't in a while.
- Use Finder's 'Go to Folder' (Command+Shift+G) to check ~/Library/Caches for oversized app caches, deleting individual app folders cautiously if you recognize them.
- If System Data stays large after cleanup, wait a few days, since macOS periodically reclaims local snapshot space automatically.
Tools and parts
- None required
External drive for archiving filesSearch: “portable external hard drive or SSD”
When to call a pro
This is almost always resolvable yourself; professional help isn't typically needed for storage cleanup.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.