mac storage full: what to do, even when there's no obvious reason
by sumit paul · last updated
when your mac's storage is full, open apple menu › system settings › general › storage to see which category is largest, empty the trash, and clear the downloads folder. if it fills up "for no reason", the cause is usually hidden: system data (time machine snapshots, caches, developer files), old iphone backups, icloud files that downloaded back to the mac, or deleted photos still waiting in recently deleted.
first 5 minutes: get some room back
a mac with almost no free space gets slow and unstable, so get a little headroom before investigating.
- empty the trash: control-click the trash in the dock, choose empty trash. a file in the trash still uses space until you do.
- open your downloads folder, sort by size, and delete installers, zip files and disk images you've already used.
- in photos, open the recently deleted album and delete all. deleted photos otherwise stay there for 30 days.
- restart. this clears swap and temporary files, and often gives back several gigabytes on its own.
find what's actually using the space
open apple menu › system settings › general › storage and let it finish calculating. each category has an info button (ⓘ). the ones that let you delete things directly:
- documents: shows large files and downloads, with a file browser to see which folders are big.
- applications: sort by size or last used and delete apps you don't need.
- ios files: iphone and ipad backups and firmware stored on the mac.
- messages: large attachments, sorted by size.
- tv, music, podcasts: downloaded media you can stream again.
the same pane offers recommendations: store in icloud, optimize storage (removes apple tv movies and shows you've watched, and keeps only recent mail attachments) and empty trash automatically (removes items after 30 days in the trash). turn on the ones that suit you.
why it fills up for no reason
| hidden cause | how to tell | fix |
|---|---|---|
| time machine local snapshots | system data is large; tmutil listlocalsnapshots / lists many | sudo tmutil deletelocalsnapshots / |
| caches and developer files | system data is large; ~/Library is big | see shrinking system data |
| icloud drive files downloaded back | the icloud drive row is large | control-click files › remove download |
| photos library with originals kept | the photos row is large | photos › settings › icloud › optimize mac storage |
| old iphone backups | the ios files row is large | finder › your device › general › manage backups |
| deleted mail still stored | the mail row is large | mail › mailbox › erase deleted items |
purgeable space confuses the numbers
apple counts the space used by time machine local snapshots as available, and macos clears caches and logs on its own when it decides space is needed. that's why finder may say you have plenty of room while an installer says you don't. macos frees purgeable space when it decides it's needed, not when you'd like it to. deleting snapshots and restarting gets the two numbers closer.
icloud doesn't free space right away
with icloud drive's optimize mac storage on, macos keeps recently opened files on the mac and only removes older ones when space is needed. so after you open a few big files, they stay. you can push a file back to the cloud yourself: control-click it in finder and choose remove download. more in how optimize mac storage works.
find big files with terminal
if storage settings still doesn't explain it, this lists the largest folders in your home folder:
du -sh ~/* ~/Library/* 2>/dev/null | sort -h | tail -20
give terminal full disk access first (system settings › privacy & security › full disk access) so it can read every folder. look for things like an old video export, a virtual machine, a game, or a forgotten project folder.
stop it filling up again
cleaning buys time; it doesn't add space. internal storage on current macs can't be upgraded, so if your own files have outgrown the disk, they have to live somewhere else:
- an external ssd is fast and has no monthly cost, but it has to be plugged in.
- icloud drive with optimize mac storage is built in and good for documents, but opening a file downloads all of it, and you'll need an icloud+ plan beyond the free 5 GB.
- google drive or dropbox's own apps keep files online-only until you open them, then download the full file and keep it.
when the problem is large files, like video, raw photos or archives, a streaming drive avoids the download entirely. feather drive puts google drive and dropbox in finder and fetches only the part of a file an app reads, so a 40 GB video opens without needing 40 GB free. in our test a 1.22 GB video opened in 1.7 s, against 1 min 44 s in google drive for desktop, which downloaded the whole file first. its limits: macos 26 or later, google drive and dropbox only, it only sees files you put in it, it needs an internet connection to open files, and it's paid after a 3-day free trial.
related
- why system data is so large, and how to shrink it
- how to free up space on a macbook air
- icloud optimize mac storage: on or off?
- how to get more storage on your mac without buying a new one
common questions
why is my mac storage full when i deleted files?
deleted files stay in the trash until you empty it, and photos you delete stay in the photos app's recently deleted album for 30 days. emptying both is often enough to get the space back.
why does my mac say storage is full but finder shows free space?
macos counts some space as available even though it is in use, such as time machine local snapshots, and frees it only when it decides the space is needed. some apps and installers don't count it the same way, so the numbers disagree until it's freed.
what happens when a mac runs out of storage?
apps slow down or quit, files fail to save, and macos updates won't install. free some space before you do anything else, starting with the trash and the downloads folder.
can i add more internal storage to my mac?
no. the storage in current macs is built into the main board and can't be upgraded. you can only free space, or move files to an external drive or the cloud.