USB memory sticks, or “Flash drives,” are handy devices for transporting data from one computer to another, and also to keep backups of your work. USB ports are common to all types of computer, whether they run a Mac, Windows or Linux operating system. Flash drives come pre-formatted, but not all formats are compatible with all operating system. This can make it necessary to reform the stick on your Mac. Reformatting also has the advantage of clearing out any hidden files that have been written to the stick that aren't in use any more. This means more space can be made available after the formatting process.
Remove any other USB devices before inserting the stick you want to format. This avoids confusion because only one memory stick will show up in the formatting utility and so you cannot mistakenly format a different device.
Insert the stick into a USB port. The operating system will perform a check on the memory stick and make it available as a drive on the computer.
Open a “Finder” window on the Mac and select “Applications.” Within this section, you need to find “Utilities” and then select “Disk Utility,” opening it by double-clicking.
Locate the memory stick in the left panel of the Disk Utility. This panel shows all available drives. Click on the Memory stick record in this panel and the main window will show details of the drive.
Click on the “Erase” button, which is located at the top of the main panel of the Disk Utility. Click on the Format drop down list. This presents a list of format options. If you intend to use your memory stick on different operating systems, select “MS-DOS (FAT).” If you are sure you will only be using the stick on your Mac, select “Mac OS Extended (Journaled).” If you can be sure that you will only be working with newer computers, running Windows XP Service Pack 2 and Mac OS 10.6.5 or later, choose ExFAT. Next enter a name for the device.
Press the “Erase” button at the bottom of the screen. A pop-up window will ask you to confirm the action. Press the “Erase” button in this window and then wait for the process to terminate.