mac disk utility how to format micro SD card as fat32

I have an iMAC, its up to date and running macOS Mojave 10.14.5

I have a microSD card adapter and an 8GB micro SD card.

When I launch Disk Utility version 18.0 and insert the adapter with the micro SD card inserted, I can see it popup in the left side bar of Disk Utility.

Now I select Erase, and supply a Name of 8GB. In the Format drop down I see options:

 Mac OS Extended (Journaled) Mac OS Extended (Case-sensitive, Journaled) MS-DOS (FAT) ExFat MS-DOS (FAT16)

I read online that MS-DOS (FAT) is supposed to be Fat32, so I chose that and clicked the "Erase" button.

The progress dialog appears and very quickly completes, if I click on the Show Details, the summary shows:

 Unmounting disk Erasing 512 bytes per phsyical sector /dev/rdisk3s1: 122604 sectors in 30651 FAT16 clusters (2048 bytes/cluster) bps=512 spc=4 res=1 nft=2 rde=512 mid=0xf8 spf=120 spt=32 hds=16 hid=8192 drv=0x80 bsec=122880 Mounting disk Operation successful

As the summary shows, this isn't FAT32 at all, so there appear to be two FAT16 options in the list, why and how can I fix this?

1 Answer

For anyone else having this problem I managed to resolve it, using the View menu of Disk Utility, ensure Show All Devices is ticked. Then another level of nodes are added to the tree view in the left side bar, the USB drive now appears under "Mass Storage Device Media", selecting this then "Erase" with type MSDOS (FAT) takes longer and does format the device as FAT32.