How to fix incorrect storage statistics and negative values on Mac?

That readout is not terribly useful, but it is based onSpotlight so if you're seeing something odd like that, you may need to rebuild the Spotlight index.

Rebuild the Spotlight index on your Mac - Apple Support

If that doesn’t work, Copy/Paste this into Terminal. sudo will ask for your password. Just type the password and hit return. It won't show anything on screen. Those two commands essentially nuke all the Spotlight records then force a reindex. You may need to restart or log out/in after running the commands.

sudo mdutil -X /; sudo mdutil -i on /

Spotlight re-indexes your Mac after a macOS update, and this process can take some time.

About Spotlight indexing and search results on Apple devices - Apple Support

You should aim to have 15-20% of your total internal storage as free space (~30-40 GB as an absolute minimum). If you do not have enough free space on your Mac’s internal storage, then here are some steps to take to safely free up space:

Free up storage space on Mac - Apple Support

Optimize storage space on your Mac - Apple Support

How to free up ‘System Data’ and other st… - Apple Community

"System Data" comprises your data, but they are typically hidden files that Spotlight cannot assign to a specific category like Documents or Applications. Examples include Outlook attachments, iOS updates, Cloud storage caches, etc. Starting with macOS 27 Golden Gate, System Data also includes what macOS used to call ‘purgeable’ storage – system caches, Time Machine snapshots and some other data, though the user had no control over the purging. Trying to manually clean out hidden files in System Data is likely to cause more problems than it solves, macOS hides those files for a good reason. Follow the steps in the linked articles above. 

On macOS 27, separate ‘purgeable’ space is no longer reported, and instead those data are now considered as used space. They are also now included in System Data, accounting for the apparent increase you (and others) have noticed. You didn't lose space, macOS just categorizes things differently now than on Tahoe.

More detail on this change in this User Tip:

System Data and Free Space Changes in Gol… - Apple Community

The best advice is to just ignore the System Data category. ‘System Data’ is merely a catch-all category for files that Spotlight cannot assign to specific categories like Applications, Documents, Photos, etc. In fact, what is now shown as System Data used to be reported as ‘Other’, Apple changed the label in macOS 12 Monterey. System Data probably sounds better, but Other was closer to reality. 

ultra65 wrote:

what my mac is showing is completely incorrect data, my applications are barely over 2 GB and even if we ignore it for a while just look at the negative storage. and the calculating, I can add the bottom which keeps on playing . Someone, please tell me how to fix it

https://discussions.apple.com/content/attachment/d762577c-df4b-440c-ac9d-b9350ce01224

https://discussions.apple.com/content/attachment/a4452df7-7a90-40bd-a2f2-cfd9d29348c2

https://discussions.apple.com/content/attachment/c622b860-b0ff-4c0d-9848-48e08e78f138

[Edited by Moderator]

Original Title: Storage statistics error

I think rebuilding the Spotlight index as suggested by neuroatomist may well fix the negative values and unphysical numbers ... but the Storage tool is still of very limited value because its categories are not easily relatable to the files and folders that most users see.

I would suggest using Storeograph and/or DaisyDisk, which are two good EXAMPLES of third party tools that provide much better information for someone trying to manage their storage (there are other tools as well, a few are free, the two I mention I use myself and they are not free but very inexpensive, especially compared to buying more storage).

There are also other simple things you can do: list all your main folders (Documents, Pictures, Music, Downloads, Desktop ... etc.) by size and look within the largest ones to see what is using a lot of disk space. Also check your USER LIBRARY and its folders, again sort by size, you may be surprised at large folders in your USER LIBRARY. I just migrated my wife's iMac account to a new M5 MacBook Air we got for her to use when we travel, and I found nearly 100 GB in her user Library that consisted of older iPhone backups made to the computer for devices she no longer even has, and some of those backups include her Photos library. Since she now uses Photos iCloud and we do her iPhone backups to the iCloud, we may end up deleting all of those iPhone backups that are on the computer, thus saving ~ 100 GB. Storeograph and DaisyDisk clearly show those files, they stick out like a sore thumb.

ultra65 wrote:

Someone, please tell me how to fix it

You can't fix it. Just don't go to that System Settings > Storage display. It's worse than useless because of problems like this.

If you have a 256 GB hard drive, you might struggle to keep enough free storage. Modern versions of macOS are extremely greedy with storage. I usually tell people to keep 100 GB free if possible, but at least 50 GB free. Yesterday, I had 466 GB free at 10am. By 2pm I have 9.6 GB free. I can't explain it.

Also note that I'm talking about actual "free" storage. In most places, the operating system will only tell you "available" storage, which is often significantly different. Of course, people then get confused when they run out of free storage when they have 100 GB of "available" storage.

So you'll need to manage your storage on your own. You might consider a 3rd party storage management tool. Just don't use that System Settings > Storage display.

The simplest way to “fix” them is to not look at them. There is nothing g useful about that display. The values are not mutually exclusive. The totals are what Spotlight has determined fits into that particular category, but there is nothing that prevents a “document” from being categorized into one of the other categories. The storage size for Applications is not the cumulative size of the applications themselves. It includes data associated with the apps.