Disk Utility on OS X (macOS) shows "MS-DOS (FAT) " as one of the format options

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FAT (File Allocation Table) has many variants like FAT12, FAT16 and FAT32

My questions are mentioned below:

  1. Which FAT variant is taken when I formate disk using "MS-DOS (FAT) format?
  2. What is maximum size (for partition/disk) of FAT variant selected in question 1?

2 Answers 2


In Disk Utility, when choosing MS-DOS (FAT), the FAT version will be size appropriate. In other words, if creating a disk image of 1.4 MB it will be formatted FAT12, if 100 MB it will be FAT16 and in the case of your 8 GB Flash Drive it will be FAT32. The FAT (File Allocation Table) link in your question answers #2 however there is nothing to worry about as it's considerable larger then your Flash Drive.

The issue to be aware of is on a FAT32 volume the maximum possible size for a file on a FAT32 volume is 4 GiB minus 1 byte or 4,294,967,295 (232 − 1) bytes.

  • For screenshot, I used 8GB flash drive. In reality, I want to format 1TB Western Digital external hard-disk. Based on your explanation and my limited knowledge, 1TB can be formatted with MS-DOS (FAT) option. It will be FAT32, which is compatible with OS X/macOS, Linux and Windows 7 & above. Correct?
    – I-M-JM
    Oct 17, 2016 at 11:39
  • @I-M-JM, Yes it will be FAT32 as a 1 TB partition/volume cannot be formatted FAT16 or FAT12 because of its size. This is why I said "... the FAT version will be size appropriate ...". Oct 17, 2016 at 12:29

Apple MSDOS-FAT is FAT32; max partition size = 2T; max file size is 4GB

FAT12 and FAT16 are (as far as I remember) pre-Win95.

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