I've formatted my pen drive in FAT format but it's not showing in a Windows laptop, so I'm thinking the formatted pen drive through OS X is not compactible with other OSs. How can I format a pen drive through OS X El Capitan?

  • FAT (for drives under 4GB) should work fine. Can you format it FAT in Windows and have OS X read it? One last thing to try, in Terminal, execute the following commands: diskutil list Find the identifier of your pendrive (disk1 disk2, disk3, etc.) Then, execute diskutil eraseDisk FAT Pendrive MBR /dev/diskN where diskN is the identifier found in the first step. Post how that works out. – Allan Sep 24 '16 at 11:40
  • Possible duplicate of Flashdrive stuck at 200 MB – David Anderson Sep 24 '16 at 13:07
  • @DavidAnderson - Not a dupe. This is not "stuck" at a capacity. It can't be read. Period. – Allan Sep 24 '16 at 13:23
  • Please specify under what version of Windows are you trying to open your FAT formatted drive? Are you plugging FAT formatted drive into USB3.0 port on Windows? – alljamin Sep 24 '16 at 23:52
  • @alljamin - FAT32 was released for Win95 so I don't know what version you think he is using that's not compatible. USB 3.0 is backward compatible to USB 1.0 so this is also a non-starter. – Allan Sep 26 '16 at 1:18

OS X and macOS can't format partitions as NTFS or write to NTFS without third-party software (read is built in). Both Windows and Mac support read/write to FAT and you can erase a disk and set the format to FAT in Disk Utility which can be read in Windows. If Windows cannot read the FAT volume then this is a separate problem with the disk or Windows as it should work.


Your flash drive is partitioned using the GUID Partition Table scheme. You need to partition the flash drive using a Master Boot Record scheme. Also you should choose to only have a single partition. You can use either MS-DOS (FAT) or ExFAT formats, but the MS-DOS (FAT) format is more reliable. You do not need to use the ExFAT format unless some files exceed 4 GB in size.


I would advice formatting any drive you want to use between OS X and Windows to exFAT. exFAT supports read/write both on OS X and Windows. You can easily format you drive to exFAT using Disk utility: WD guide and official Apple forum thread.

FAT-32 also works between Mac OS X and Windows just fine, but it limits you to 4GB per-file. exFAT doesn't have such limitation.

In your question you mentioned:

I've formatted my pen drive in FAT format but it's not showing in a Windows laptop

If you want to stick to FAT-32 then try to reformat your drive once again using Disk utility on Mac or format it under Windows. On Windows you might want to uncheck the Quick format option to ensure better formatting.

Also make sure the USB port you're connecting your drive to is working and the drive itself is not corrupted.

  • How does this address the OP's question that the drive is formatted in FAT and cannot be read in a Windows laptop? – Allan Sep 24 '16 at 11:35
  • @Allan There is no problem with my answer (as far as I can see) because FAT and exFAT formats are readable and writable both on Windows and Mac. Hence the problem is with the Windows machine itself. Again, the question is "How can I format a pen drive through OS X El Capitan?". My suggestion is to go with exFAT format via Disk utility on OS X. – alljamin Sep 24 '16 at 11:51
  • FAT should work fine. Are you sure he used the right partition map? Are you certain that the USB port on his Windows box works? – Allan Sep 24 '16 at 12:00
  • @Allan I am not sure about the details of OP computer hardware as well as the way how he did his drive formatting. These two questions are worth asking in comments. – alljamin Sep 24 '16 at 12:41
  • 1
    You said, "FAT-32 limits your drive usage to 4GB - if you try to format e.g. 16GB pen drive in FAT-32 it will show up as 4GB pen drive. exFAT doesn't have such restriction." and this is utter rubbish. I have absolutely no problem whatsoever formatting my 16GB flash drive in a single 16GB FAT32 partition under OS X that works with OS X, Linux and Windows! – user3439894 Sep 24 '16 at 13:31

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