I'm in the process of installing Windows 10 on my Macbook Pro (macOS 10.13.4/17E202, 256 GB of storage, no partition), but Boot Camp says I need at least 40 GB of storage.

So I freed up some space by removing some files, and "About My Mac" now shows almost 100 GB of free space on my Mac:

enter image description here

However, the Disk Utility shows only 33 GB of free storage... 3 times less:

enter image description here

The trash is empty, and I restarted my computer twice. I also used Onyx utility to free up some more space, empty caches, etc. But there is still this huge difference.

I tried to find "hidden files", that could cause this difference, using the Disk Inventory X app, but it shows 100 GB of free storage...

Another strange thing that happened: after I restart the computer, the status bar at the end of the finder shows 33 GB of free storage. But after 2-3 minutes, this number changes to about 100 GB... As if some cached values were used while the Mac is updating the folder sizes.

I'm pretty sure I have 100 GB of free storage, because I removed dozens of GB of photos and apps.

What's wrong? I'm kind of lost!

  • Check this also: apple.stackexchange.com/questions/223390/… I have 250GB of Mail logs. – mikel Sep 4 '19 at 12:43
  • 2
    The real answer is that the Finder and About This Mac give you inaccurate information, and can't be trusted. It's really frustrating that Apple does this, especially when the Finder reports that you're out of disk space yet shows you 50GB free. Disk Utility or df -H / are more accurate. – JW. Feb 29 '20 at 20:44

You probably have some local snapshots on your drive, you can try to list the local snapshots with

tmutil listlocalsnapshots /

and with

tmutil thinlocalsnapshots / 9999999999 1

you can delete all local snapshots and release the storage space.

You can find more information here How to thin your local Time Machine Snapshots on macOS High Sierra

  • Thanks, GM. I haven't thought of Time Machine local snapshots. I have 4 of them, indeed, that were created today, probably when I cleaned my Mac. I'm currently running Time Machine, this will probably get rid of these snapshots! I'll keep you posted ;) – piko May 4 '18 at 21:33
  • 1
    That was it. I removed the snapshots and it looks like they were the "purgeable content". Thanks! – piko May 5 '18 at 0:23

Commands given below resolved the issue for me. Listed and deleted local snapshot and it freed 230 GB on my machine.

$ tmutil listlocalsnapshots /
$ tmutil deletelocalsnapshots 2019-01-28-143406  
$ tmutil listlocalsnapshots /

Make sure it shows no file at the end.


The amount of free space that can be allocated to run Windows can be determined by entering the following command in a Terminal application window. Here, I have assumed you are using a single internal drive with just macOS installed.

diskutil apfs resizecontainer disk0s2 limits

Note: This command does not change the computer in any way.

Normally, you can subtract the minimum about from the maximum to get the free space that can be allocated for Windows. Also, there is an alternate "Recommend" minimum amount when macOS is installed.

Below is an example of the output from the above command.

Resize limits for APFS Physical Store partition disk0s2:
  Current Physical Store partition size on map:   250.8 GB (250790264832 Bytes)
  Minimum (constrained by files/snapshots):       175.6 GB (175553185382 Bytes)
  Recommended minimum (if used with macOS):       186.5 GB (186453185382 Bytes)
  Maximum (constrained by partition map space):   250.8 GB (250790264832 Bytes)

In this example, the maximum space that can be allocated to Windows is 250.8 GB - 175.6 GB = 75.2 GB. Although, since you have macOS installed, the recommended maximum space that can be allocated to Windows is 250.8 GB - 186.5 GB = 64.3 GB.

Note: For 2015 an newer Macs, the maximum amounts may be reduced by the amount of storage required to hold the Windows installation files. In other words, the newest Macs no longer require a USB flash drive or DVD to install Windows. During the installation of Windows, files from both Microsoft and Apple are temporarily stored on the internal drive. This can reduce the maximum amount of storage that can be allocated to Windows. The amount of storage for these temporary files should be less than 16 GB.

  • Thanks David for your thorough answer! However, my problem isn't about allocating space for Windows, but more to free up space on my computer. In other words, I'm trying to find a way to remove the 60 GB of "purgeable content" from my disk, which could potentially be Time Machine snapshots. I'm backing up right now, let's see if that's the case! But your input will be valuable when I'll decide how much I need to the partition. Thanks! – piko May 4 '18 at 21:38

I had the same problem. After trying all sorts of things without success, i decided to erase my drive and do a clean install of High Sierra.

The first thing i did was clone the boot drive with Carbon Copy Cloner. After the clone was complete, the free space was correct (!).

I have no idea why this worked, but the finder is showing the correct free space and updates instantly when i empty the trash.

Hope this helps


To delete all local Time Machine snapshots in a single command, run this command in the Terminal, courtesy of this answer by Martin:

for d in $(tmutil listlocalsnapshotdates | grep "-"); do sudo tmutil deletelocalsnapshots $d; done

You may also skip sudo depending on your privileges.

tmutil deletelocalsnapshots deletes about 1 snapshot every 30 sec, so if you have a bunch of snapshots, it will take time.

To view the snapshots before deleting them, run:

for d in $(tmutil listlocalsnapshotdates | grep "-"); do echo $d; done

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .