Go to Applications and Utilities and launch Disk Utility.Connect the flash drive that you want to format.Your Mac computer comes with a handy utility appropriately called Disk Utility, which can be used to format any storage device. In this article, we are taking a closer look at the Disk Utility, which comes with all recent versions of the Mac OS X operating system and how you can use it to format USB drive on Mac. Some flash drives have to be formatted first before you can store files on them. Not every flash drive out there can be used with a Mac computer right out of the box.
