A:Answer I looked on the box and it says compatible with windows and Mac. Therefore, it must come formatted FAT32, which is the file system compatible with both operating systems. If you were going to use the hard drive solely with your MacBook Pro, I might recommend reformatting it in the OS X journaled format. I formatted it to the OS X jouranled format using Disk Utility because I wanted to use it as a time machine back up drive.