Ok so I have a large folder on disk see the image below

enter image description here

You can see it says the size of the folder is 8.46GB however this is mostly source code, and I think file system will be using file compression under the hood. I'd expect this folder to compress very well, so my question is this. "How can I find out how much actual physical space this folder is using?"


  • Not sure APFS already supports compression, even with Mojave. – nohillside Dec 24 '18 at 14:14
  • I think that what you are seeing is correct (i.e. 9.73 GB). No file compression in APFS. I would expect source code (with lots of small files) to be relatively inefficient due to lots of upwards rounding. And this is reflected in your numbers. – Gilby Dec 25 '18 at 22:05

You should go to the terminal and from the terminal cd to the folder you want to get the size of. Once there type: du -h. The last number it prints is the directory size.

  • It might be worth mentioning that for some time now Apple abandoned using base-2 calculations in Finder and now use base-10, while most of the BSD command line utilities still use base-2 calculations. – user3439894 Dec 24 '18 at 17:32
  • The final line in du -h is rounded to a whole number of GB. So this doesn't help much. – Gilby Dec 25 '18 at 22:09

You must log in to answer this question.

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