How to Format My Passport for a Mac
The Passport external hard drives provide expanded storage space for your various files and software in your computer system. Format the Passport drive to erase any current files stored to the hard drive and ensure the volume is compatible with your Mac's operating system. Mac OS X includes a built-in disk utility to assist you in managing hard drives and other storage devices.
Connect the USB port from the Passport to an open USB port on your Mac.
Click "Finder" and click the "Applications" folder. Click the "Utilities" folder.
Double-click the "Disk Utility" icon. Click the "Passport" entry in the left side of the window and click the "Erase" tab.
Click the "Volume Format" menu and click the "Mac OS Extended" option.
Click "Erase" to format the Passport for use with your Mac.