A 16 inch MacBook Pro with the M3 Pro or M3 Max chip has a fast solid state drive that cannot be upgraded after purchase, so when macOS says the disk is almost full the answer is to find what is large and remove or move it. Open the Apple menu, System Settings, General, Storage, and wait for the bar to fill: it breaks the space into Applications, Documents, Photos, System Data and more. The macOS recommendations, such as Store in iCloud and Optimize Storage, can help, though they depend on iCloud space, and you can open the Manage button for a list of large files.
The checks in more detail
On a professional laptop, the largest users are usually video and photo projects, caches from editing software, virtual machines, Docker images, Xcode files and old iOS backups. Go through those in order. In Storage, review Documents, which lists the biggest files, and move projects you are not using to an external drive or cloud storage. Empty the Trash, which stays full until emptied. Remove old iPhone and iPad backups under General, Storage, iOS Files or in Finder.
Video and music editors keep render caches and proxies; clear them from inside each app. A developer will find Xcode's derived data and simulators large, deleted through Xcode's settings and command line. System Data may look large because of caches and logs and local Time Machine snapshots, and a restart clears some, while macOS removes snapshots when space is needed. A full drive slows the Mac because it has no room for swap files and updates, so keep at least ten to fifteen percent free.
If the drive is persistently full, use a fast external SSD over Thunderbolt for projects, and a network storage for archives. Do not delete files in the System or Library folders unless you know what they are. If Storage reports huge System Data that does not shrink after a restart, boot into Safe Mode by holding the power button at start-up and choosing the disk with Shift held, which clears some caches, then restart. Back up with Time Machine before large deletions. If the figures look wrong, contact Apple Support.
Differential
Likely causes of “Apple MacBook Pro 16-inch (M3 family) storage is full or nearly full”, and how to tell them apart
- 1
Large project and media files
What separates it Documents and Photos are huge
How to confirm Move them to an external SSD or the cloud
- 2
Editing caches and renders
What separates it Apps hold gigabytes of cache
How to confirm Clear them in each app
- 3
Old device backups
What separates it iOS Files is large
How to confirm Delete old backups
- 4
Developer files
What separates it Xcode and virtual machines
How to confirm Remove derived data and unused images
- 5
Snapshots and caches
What separates it System Data is large
How to confirm Restart; macOS frees snapshots when space is needed
Before you touch a setting
Record this first — changing settings destroys the evidence
- The storage breakdown
- The largest category
- Whether the Trash is full
- How much is free
Try in this order
0 of 6 completedOpen the storage view
ReversibleIn System Settings.
Review the largest files
ReversibleIn Documents.
Empty the Trash
ReversibleAnd remove old backups.
Clear app caches
ReversibleIn each app.
Move projects off the Mac
ReversibleTo an external SSD.
Restart
ReversibleTo free temporary files.
Model-specific
What is true of this model and not of its siblings
- Fixed storage
- It cannot be upgraded.
- System Data
- It includes caches and snapshots.
Stop boundary
When this stops being a self-service repair
- !If the figures stay wrong after a restart and Safe Mode, contact Apple Support
- !Leave macOS’s required files in place
- !Back up first
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Can I upgrade the MacBook Pro's storage?+
No, it is built in.
What is System Data?+
Caches, logs and snapshots.
How much should I keep free?+
Ten to fifteen percent.
Is an external SSD a good fix?+
Yes, for projects.