Difference in FAT32 format (MacOS, Windows, Linux)

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Difference in FAT32 format (MacOS, Windows, Linux)

Is there a difference between how MacOS and Windows/Linux format USB flash drives into FAT32?

I have a device that uses custom USB drivers and is compatible only with FAT32. When I format to FAT32 using MacOS, the device cannot read it, but PC can; when I format into FAT32 using Windows, the device can read is and so can MacOS.

I suppose there are advanced USB drivers that PCs are using, but I wonder if there is somewhere documentation to FAT32 formatting or if anyone can explain this to me or point me to the right direction.

Posted on Oct 4, 2021 12:43 AM

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Answer 1

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Luis Sequeira1

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Oct 4, 2021 1:02 AM in response to shadowprice

In theory they all should work, but maybe there is something you may have missed.

Typically drives formatted for the mac use GUID Partition Map but FAT32 drives use Master Boot Record. In Disk Utility one can choose which to use. Maybe your drive got formatted as FAT32 with GUID and the device does not recognize that combination.

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Answer 2

Oct 4, 2021 2:25 AM in response to shadowprice

As Luis said, the partition scheme might explain this.

The lowest common denominator seems to be MSDOS-FAT with Master Boot Record and I use that if I want to be certain the the USB drive works in Windows, smart TV, drone, camera etc (although I always let the drone and the camera format the card).

Previously I thought that Windows 10 is happy with exFAT with the more modern GUID and this worked OK until a few days ago I had several GB to transfer over sneakernet and was surprised that a 128 GB flash drive showed only AFAIR 200 MB free on Windows 10 although I then tried to format it also on Windows. With my limited Windows permissions I could not then use any more advanced formatting options. At home I then formatted the flash drive as exFAT Master Boot Record and then also Windows showed all about 128 GB free space. AFAIK some Windows exFAT (block size?) options are not compatible with Mac but the Windows 10 default seems to be OK also on Big Sur.

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Answer 3

shadowprice Author

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Oct 5, 2021 1:26 AM in response to Luis Sequeira1

This was very helpful. I indeed found out that GUID seems to be causing issues, and MBR works fine.

The partition scheme was not visible to me at first, because you can see that only when you format the whole disk and not just the one particular partition (disk 15Gb -> has 15Gb partition). This was visible to me only when I enabled show all devices in Disk Utility.

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Difference in FAT32 format (MacOS, Windows, Linux)

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