How to partition and format an external hard drive on a mac

Here is a quick and easy way to format an external hard drive on a mac computer using the disk utilities partition tab. Make sure the external hard drive is connected either via USB or Firewire 800 directly to the mac computer.

If the hard drive is detected correctly it will mount on the desktop and you should be able to read and write to the external hard drive or read only if it has been formatted as FAT32 or NTFS.





Now navigate to the Applications > Utilities folder and launch the Disk Utility application.

Locate the external hard drive on the list to the left and highlight the capacity. Now under the Partition Layout, select 1 Partition.

Now next to Format, select Free Space.

Now click on the Options button located near the bottom of the screen and select GUID Partition Table then click OK.

Now click the Apply button and confirm the change by clicking the Partition button.

You have now successfully erased the hard drives old data and partition information. You can now repeat the same steps to create a new partition and format the external hard drive as Mac OS Extended (Journaled).

Now under the Partition Layout, select 1 Partition. Now next to Format, select Mac OS Extended (Journaled).

Now click on the Options button located near the bottom of the screen and select GUID Partition Table then click OK. Now click the Apply button and confirm the change by clicking the Partition button.

You have now successfully created a new partition and formatted the external hard drive, it is now ready to be used on your mac computer.

Note: To use the external hard drive on a mac and pc (cross-platform), just select MS-DOS (FAT) from the Format menu.