How to format a thumb drive using macOS Monterey, lead image.
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Occasionally the need arises to use a thumb drive to store, back up or transfer files. Fortunately, Mac users can take advantage of a flash drive’s convenience just as Windows users can.

The first step involves physically connecting common thumb drives to a Mac. Although Windows machines typically include the larger USB-A ports needed to accommodate common thumb drives, many contemporary Macs ship only with thinner, more compact USB-C ports. Apple’s $19 USB-C to USB adapter, as it’s known, solves that problem by permitting connecting common USB-A accessories to a Mac’s USB-C or Thunderbolt 3 ports.

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The next step involves configuring a thumb drive’s file storage system to work with a Mac. While Macs typically use a file format known as APFS or Mac OS Extended, and Windows systems often use NTFS or ExFAT, FAT remains a commonly used file system on thumb drives, as that format permits reading and writing files using both PCs and Macs.

Thumb drives, by default, often ship with a Windows file system incompatible to Macs. When these incompatibly formatted thumb drives are connected to a Mac, macOS displays a warning, as shown in Figure A.

Figure A

Warning message, incompatible thumb drive.
macOS permits formatting thumb drives even when the devices possess an incompatible file system.

In such cases, choose Initialize to proceed. The Disk Utility will open, as shown in Figure B.

Figure B

Mac Disk Utility opens.
The macOS Disk Utility permits formatting thumb drives and changing file formats.

Enter a title for the thumb drive within the Name field. Alternatively, you can leave the Name field unchanged, and macOS will name the thumb drive UNTITLED.

Next, using the drop-down menu, update the Format field from Mac OS Extended (Journaled) to ExFAT or MS-DOS (FAT) and leave the Scheme field unchanged. Before clicking Erase, note that changing or converting a file system on a thumb drive deletes all data on the device. You should also always double-check to ensure you’re preparing to change the thumb drive’s settings and not the Mac’s actual hard disk, and you should only work with USB drives of known provenance; in other words, don’t connect any unknown or untrusted USB device to your Mac.

If losing all the information on the thumb drive poses no trouble, you trust the USB device and you’ve confirmed you’re about to change the thumb drive’s disk settings and not the Mac’s, click the Erase button. But if you need to back up the drive’s data to another location before proceeding with the formatting operation, be sure to complete that step first.

When you click Erase, macOS will initialize the thumb drive using the file format you specified. Once the process completes, macOS will display an operation successful message, as shown in Figure C.

Figure C

Success message after clicking Erase.
When finished, macOS confirms the file format conversion is complete.

SEE: macOS Monterey: A cheat sheet (free PDF) (TechRepublic)

Click Done to close the window. The thumb drive is now ready to use, both on Windows PCs and Macs.

The process proves a little different if the thumb drive was previously configured for a Mac. Should that be the case, and should you now wish to convert the file system to FAT to also permit using the device with a Windows PC, open the macOS Disk Utility by opening Finder, selecting Applications and double-clicking the Utilities folder and then the Disk Utility entry.

Next, select the thumb drive, click Erase, then enter a name for the drive and specify ExFAT or MS-DOS (FAT). Both ExFAT and MS-DOS (FAT) work with thumb drives and Windows PCs and Macs. ExFAT permits using larger file and partition sizes, among other advantages, but because I need the drive to be compatible with an automotive component requiring FAT32, I’ve chosen MS-DOS (FAT) for this example.

Once you’ve entered your format selection, clicking the Erase button, as described above, executes the changes.

Should you need to alter a thumb drive’s configuration, such as specifying a new name for the device, just open the macOS Disk Utility and enter a new title, as shown in Figure D.

Figure D

Renaming a thumb drive.
Using macOS Monterey, users can change a thumb drive’s name and format repeatedly, should they need to.

When the thumb drive is subsequently connected to a Windows system, you can use the device to store, back up and transfer files just as when connected to a Mac. As you can see in Figure E, the device appears within Windows as a FAT32-configured USB drive.

Figure E

Connecting the reformatted drive to a Windows system.
A USB drive formatted with the FAT file system works when connected either to Windows PCs or Macs.