I did a copy and paste of files from my MacBook Pro (2018) 15-inch (Mac OS 10.13.16)’s 256GB SSD (formatted APFS) to my 2TB WD My Passport hard drive (formatted HFS+).

I wanted to confirm that all the files were copied correctly. However, when I compared the Finder’s “Get Info” panel for the original folder VS the folder in the hard drive, I saw that the sizes weren't the same.



I decided to compare each individual file sizes in the folders on Finder using the “Size” column. I had one window showing the files of the original folder side-by-side another window showing the files of the new folder in the 2TB WD My Passport. Each individual size of the files were the same.

Why does “Get Info” show different sizes of the folders? Is Finder the most accurate way of finding the size of a file or folder? If no, which tool (command-line is fine) is the most accurate?

NOTE: (1) I selected all the files from the original folder and used Command+C in Finder directly on these files. I then put the copied versions of the files (the ones on the hard drive) in a new folder. I did not select the original folder and copied the folder. (2) The new folder name on the hard drive is different from the original folder name (3) I followed some suggestions on Same Files in Two Folders, But Different Size Info?. I did not spot any hidden files.

  • 1
    They're exactly the same size - 9,731,676,356. Any discrepancy is in how the data fits the drive's block size. By copying it you in effect defragged it too.
    – Tetsujin
    Aug 11, 2019 at 15:27
  • The 2 get info windows report the exact same size of 9,731,676,356 bytes. You were looking at the 9.78 and 9.73 numbers. These probably represent the approximate size on disk these occupy and may be dependent on minimum storage size on the 2 disks. It will be higher on the 2 TB drive.
    – Natsfan
    Aug 11, 2019 at 15:35
  • I am referring to the part that says size...(9.78 GB on disk). One says 9.78, another says 9.73. Aug 11, 2019 at 15:35
  • So is it more accurate to read the XXXXXX bytes part VS the (XXX GB on disk) part of the Get Info panel? Aug 11, 2019 at 15:36
  • @jmh, but note, the pane reporting 9.73 (the right one) is the one from the 2TB hard drive. The one reporting 9.78 is on the SSD. Aug 11, 2019 at 15:37


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