Out of disk space after Sequoia Upgrade

245 GB drive is really a 256 GB

A 256 GB Drive in 2025 is equal to when Apple Sold the Tiny Level Laptops with the tiny 128 GB Drives

What follows is not popular for some, though very effective

The more  popular and effective ways to address this issue is to Start Over from Scratch 

For Apple Silicon computer >> Use Disk Utility to erase a Mac with Apple silicon.

For Apple Intel computers >>   Use Disk Utility to erase an Intel-based Mac followed by How to reinstall macOS

Always make a Time Machine Backup  before  proceeding 

It is also suggest to  Only Migrating the User Account and nothing more.

Emphasis on User Account Only

Reinstall the Needed and not the Wanted applications from the Apple Apps Store or Directly from the Developers 

Generally when this issue is discovered by the User ( you in this case )

It is because the Internal Drive Capacity of this computer maybe on the small size

Unfortunately, the users' current needs for Storage may have grown since the time it was originally purchased 

The implications being that on your next purchase

Spend the Extra Money Up Front on a larger Drive Capacity Drive and add more RAM

This may just Future Proof the computer for your growing needs 

toddcscar42 wrote:

Results from several of the suggestions:

* Understood solution to backup, erase, and restore. This just started happening after the last OS release. Machine has been fine for 3+ years. If you look at how much data I have it isn't much. I dont have "growing needs"

* Disk Utility shows free space of 2.75 GB

* diskutil list internal

shows "Macintosh HD" at 11 GB

If you choose to do the " Erase All Content and Setting "

This time, do not migrate anything at all

Install your applications directly from the Apple Apps Store and Developers

Come back and report your finding.

I suspect but can not confirm, without using another application, when this computer was initially setup

There was a migration from another computer

In either case, "Disk Utility shows free space of 2.75 GB "

Doing the math, 256 GB Drive Capacity by 2.75 GB Free space

This represents 98.92% of the entire 256 GB Capacity is Used

I speak for myself here

If this condition is left unattended to, this may risk creating a new issue that could be avoided

You are fortunate, so far, the computer may not even boot up at all in this condition

Ronasara wrote:

Never use third party applications to clean your drive. They will only cause problems and relieve you of your money.

Agree.

I recommending buying an external drive and then transferring files such as photos, music and videos over to it. Then delete them from your HD to clear needed space. This will solve your space problem.

The OP's list indicates that Photos and Documents are using <1 GB of the storage, so I doubt that copying off and deleting such files will help. System Data comprises >80% of the storage used, and those files are not ones readily accessible for copy/delete.

toddcscar42 wrote:

* diskutil list internal

shows "Macintosh HD" at 11 GB

That 11 GB is the Recovery OS.

Disk Utility shows free space of 2.75 GB

That is woefully inadequate. Short of the nuclear option, you could boot into recovery mode and reinstall macOS with the option to preserve your user data.

System Data (formerly called 'other') is mainly your own data stored within application containers in the hidden Library folders. Email attachments are a frequent culprit.

What is “Other” storage on a Mac, and how… - Apple Community

211 GB is definitely weird and unreasonable. The System Data category includes logs, caches, temp files, VM, and the like. The OS definitely should be cleaning that stuff up.

I will occasionally use an app called OnyX to run multiple cleanup scripts manually, and this looks like a reasonable candidate for a good, comprehensive flush.

Before doing that, though, crack open a root-level Finder window in List view. Cmd + J to show View Options and check the 'Calculate all sizes' box near the bottom. Then you can sort by size, do a little digging, and maybe find a decent clue that way.

Never use third party applications to clean your drive. They will only cause problems and relieve you of your money. If your drive gets too full the computer can stop functioning and then you have a serious problem to deal with. I recommending buying an external drive and then transferring files such as photos, music and videos over to it. Then delete them from your HD to clear needed space. This will solve your space problem.

Time Machine local snapshots can accumulate as well— clear this by running your TM backup...(?)

Do some house cleaning if you are choked full. the macOS likes to have 15-20% free storage to operate efficiently.

That GUI is notoriously confusing if not inaccurate.

you seems to have a very tiny storage capacity by today's standards, so an external drive seems a good recommendation.

23GB macOS seems unusual...(?) I would expect Sequoia to be ~ 11.2GB

you can see the big epicure from the Terminal.app copy and paste:

diskutil list internal

your user data which you have control is the : "Macintosh HD - Data"

you can see an itemized list of your user folders, copy and paste:

 sudo du -gs ~/* | sort -k 1nr 

( note: your psswd will not echo, type it in anyway, to proceed Enter/Return key)

leroydouglas wrote:

23GB macOS seems unusual...(?) I would expect Sequoia to be ~ 11.2GB

Yes and no. On my two MBPs, macOS 15.5 reports 21-23 GB but clicking on the (i) next to the size gives a popup showing that Apple Intelligence is using 10-12 GB (even though I have it set to OFF on both computers).

Mainly /Library and ~/Library. Depending on what applications you have, Shared can be a culprit (e.g. some video surveillance apps write the continuous recordings there).

As leroydouglas notes, the System Settings > General > Storage GUI can be inaccurate. Open Utilities > Disk Utility, select the top level container disk, what does it show for free space?

One other trick is to toggle invisible files in Finder with Command-Shift-Period. I would not recommend deleting anything you see that way as a space-hog (macOS makes files invisible for good reason), but finding something may help troubleshoot.

toddcscar42 wrote:

Results from several of the suggestions:

* diskutil list internal

shows "Macintosh HD" at 11 GB

MacBook Air 13″, macOS 15.5

That seems more reasonable ...

I hardly suspect with " free space of 2.75 GB " you would be able to successfully upgrade to the latest update 15.6

and see if there was some relief.