macOS · Mac · Speed & performance

Keep 10% of your disk free

macOS needs headroom for swap and caches. Under about 10% free space, everything — including Time Machine — starts to crawl.

DifficultyEasy
Time10 min
RiskLow
ReversibleYes
PlatformmacOS
UpdatedOct 3, 2026

Written and tested by emdottech

What that means

Low risk. This fix only checks things, or changes settings you can switch back in the same place. This change is reversible — you can return to the previous state without professional help or data loss.

A disk usage bar showing the last ten percent free space zone highlighted as the headroom macOS needs

Steps

01
- macOS Ventura or later:Apple menuSystem SettingsGeneralStorage(Monterey and earlier:Apple menuAbout This MacStorage tab) — sort categories by size and delete what you don't need (Applications, Documents, System Data)
02
- Sort items by date last used — the oldest offenders are usually safe to move to an external drive
03
- Empty the Trash (FinderEmpty Trash) and clear out Downloads; set Finder → Settings → Advanced → 'Remove items from the Trash after 30 days'
04
- Photos library is huge? Photos → Settings → iCloud → Optimise Mac Storage keeps full-resolution copies in the cloud

How to verify the fix

System Settings → General → Storage (Monterey and earlier: About This Mac → Storage tab) shows about 10% or more free space, and Time Machine backups run without warnings.

If this didn't fix it

Free space drops below 10% again within days — a single app or cache is regrowing; sort by size to find it.

Next stop: the related fixes below, or start a guided diagnosis.

Still stuck? Diagnose my problem Browse all Mac fixes

Keep 10% of your disk free

Steps

✓How to verify the fix

!If this didn't fix it

Related fixes

How to verify the fix

If this didn't fix it