Mac storage full? What to do when your disk is almost full

What "storage full" means on a Mac

When free space on your startup disk runs low, macOS shows a notification that says "Your disk is almost full" and suggests optimizing storage. It's worth acting on. A Mac with very little free space can't install updates, apps can fail to save files, and macOS has less room for the swap files and snapshots it uses in the background.

A full disk is almost never one thing. It's a few large items, and the job is finding them. This guide starts with the tools built into macOS 15 Sequoia, macOS 26 Tahoe and macOS 27 Golden Gate, which all use the same Storage settings. If you only want the cause, what's taking up space on your Mac goes deeper into finding it.

Keep an eye on free space

You don't have to open System Settings to see how close you are. In Finder, choose View > Show Status Bar, and the bottom of every Finder window shows how much space is available on that disk. Check it again after each step below, so you can see which ones made a difference.

Why your Mac's storage is full

The same categories fill most Macs:

• Photos and videos. The Photos library keeps full-size originals unless Optimize Mac Storage is on.
• Downloads. Installers, disk images and one-off files you opened once.
• iPhone and iPad backups. Each one is a full backup of a device, kept by Finder.
• Messages and Mail. Attachments stay on the Mac with the conversations and emails they came in.
• Apps and games. Some bring large libraries of their own, such as sound packs or game data.
• Developer tools. Xcode, simulators, Docker and package managers can each take many gigabytes.
• System Data. Caches, logs, local Time Machine snapshots and app data in your Library.
• The Trash. Things you moved there still take up space until you empty it.

Step by step: get space back safely

Work from the top. The early steps cost nothing and are easy to undo.

1. 1

   Open Storage settings

   Choose Apple menu > System Settings, click General in the sidebar, then click Storage. Wait until the bar finishes calculating, then hover over it to see each category's size.

2. 2

   Use the recommendations

   Under Recommendations, turn on Store in iCloud, Optimize Storage or Empty Trash automatically if they suit how you work.

3. 3

   Empty the Trash

   Check what's in the Trash, then choose Finder > Empty Trash. Files in the Trash still use space until it's emptied.

4. 4

   Clear old downloads and large files

   Click the Info button next to Documents to see large files and downloads. Move what you no longer need to the Trash in Finder, or to an external drive if you want to keep it.

5. 5

   Remove old device backups and apps you don't use

   Check iOS Files for old iPhone and iPad backups, and Applications for apps you no longer open. Make a fresh backup of a device before you remove an old one.

6. 6

   Restart and check again

   Restart so macOS can let go of swap files, then open Storage settings again to see what changed.

The first stop is Apple menu, then System Settings, then General, then Storage. Apple's storage guide describes the three recommendations you'll see there:

• Store in iCloud keeps Desktop and Documents files, photos and messages in iCloud, and keeps only recent files on the Mac when space is needed.
• Optimize Storage removes Apple TV movies and shows you've already watched, and keeps only recent Mail attachments on the Mac when space is needed.
• Empty Trash automatically erases items that have been in the Trash for more than 30 days.

Store in iCloud uses your iCloud storage, so it may mean a larger iCloud plan. All three are optional; turn on only what fits how you work.

The quickest wins

After the Trash, these usually free the most for the least risk.

• Old downloads. Disk images and installers in Downloads can go once the app is installed. Sort Downloads by size in Finder's list view to find the big ones.
• Large files. Click the Info button next to Documents in Storage settings and look at Large Files. Find large files on a Mac covers Finder and Terminal methods.
• Device backups. iOS Files lists iPhone and iPad backups. Keep the newest one for each device you still use. See delete old iPhone backups.
• Apps you don't use. The Applications category lists apps with their sizes. An app's support files live elsewhere, so uninstall apps completely explains how to catch those.
• Messages attachments. The Messages category in Storage settings lists the photos, videos and files in your conversations. Removing one also removes it from its conversation, so save any you want to keep first.
• Video. Move finished projects and old screen recordings to an external drive.

If you use iCloud, turn on Optimize Mac Storage in two places. For iCloud Drive, open System Settings, then your name, then iCloud, then Drive. For Photos, open Photos and choose Photos > Settings, click iCloud, then select Optimize Mac Storage, as Apple's Photos guide describes. With both on, macOS keeps older documents and full-size originals in iCloud when space is needed.

When System Data is the biggest part

If the gray System Data segment dwarfs everything else, most of the steps above won't touch it. Check for local Time Machine snapshots first, since they're the most common cause and macOS frees them on its own. Then look at caches and app data in your Library. System Data on a Mac walks through it, and Time Machine local snapshots and purgeable space explain the parts macOS manages itself.

If you deleted a lot and the numbers barely moved, why Mac storage doesn't add up explains the usual reasons.

If you can't free enough to work

If the disk is so full that apps won't open or an update won't install, Apple suggests starting up in safe mode. Safe mode clears certain system caches, which can free enough room temporarily to finish an update. Restart normally afterwards. Then make lasting room: copy large media to an external drive, check it opened correctly there, and only then remove it from the Mac.

Why Mac storage keeps filling up

Some space comes back no matter what you do. Apps rebuild their caches within days, Time Machine makes a new snapshot every hour, and Messages, Mail and Photos keep adding to their libraries. Moving a cache to the Trash frees space only until the app fills it again.

The cleanups that last are the ones that don't regrow: old downloads, backups of devices you've replaced, apps you no longer use, build data for finished projects, and duplicate copies of files. It helps to know which is which before you start.

Space that lasts

Example numbers

Moved to the Trash

14.5 GB

Came back in a month

1.7 GB

Stayed free

12.8 GB

1 day+800 MB

1 week+1.5 GB

1 month+1.7 GB

Stayed freeCame back

Space that lasts by rule, after a month

Rule	Freed	Came back	Stayed free
Xcode DerivedData	7.4 GB	1.2 GB	6.2 GB
Package manager caches	6.3 GB	300 MB	6.0 GB
Editor caches	600 MB	200 MB	400 MB
App logs	200 MB	0 GB	200 MB

What's safe to remove and what isn't

Usually safe: the Trash once you've checked it, installers and disk images in Downloads, old device backups after a fresh one, apps you no longer use, old logs and crash reports, and caches, with the catch that caches come back.

Leave alone: anything in the System folder, the Library folders of apps you use, your Photos library's internals, Mail and Messages folders, iCloud Drive files you haven't backed up elsewhere, and anything a Terminal tip tells you to remove with sudo rm.

The Trash is your safety net. Until you empty it, anything you moved can go back where it was.

How MacClearings does it

MacClearings starts with the same question you have: what's filling the disk, and what can go. The Overview shows your startup disk as a ring. Gray is what you keep, color is what MacClearings could move to the Trash after you review it, and purgeable and free space are shown separately, so you don't count space macOS will free anyway.

Suggestions groups what can go by kind, from developer data to logs and old downloads, and each rule says in plain words why it's usually safe. Only things that are safe to lose and don't come straight back are checked for you; app and browser caches and device backups start unchecked. Nothing moves until you review the full list. MacClearings then moves what you confirm to the Trash, and History can undo the whole cleanup or put back one item.

The space comes back when you empty the Trash, which MacClearings never does for you. Afterwards, it measures each cleaned place again after a day, a week and a month, so you can see what stayed free.