You can use Disk Utility to format a disk for Windows computers. You can choose one of several MS-DOS formats.
WARNING: Formatting a disk erases its files. Copy files you want to save to another disk before formatting the disk.
In Disk Utility, select the disk you want to format for Windows computers.
Click Erase and choose MS-DOS File System from the Volume Format pop-up menu.
Type a name for the disk.
The name's maximum length is 11 characters.
Click the Erase button, then click Erase again.
You can also choose to partition a disk using a Windows partition scheme which formats the partitions in MS-DOS format.
