Format an External Hard Drive or USB Flash Drive for Mac OS X

How to Format an External Drive for Mac Compatibility

This is a simple procedure and is achieved the same way for all drive types and through all connections, be they USB, Firewire, or Thunderbolt. Formatting a drive will erase all data and partitions on the disk:

1. Connect the hard drive or USB key to the Mac
2. Launch Disk Utility, located in Applications > Utilities
3. Locate the drive name from the left hand side of Disk Utility and click on it
4. Click on the “Erase” tab across the top

5. Next to “Format:” click the contextual menu and select “Mac OS Extended (Journaled)”

6. Name the drive if you want, the name can be changed at any point
7. Click the “Erase” button and confirm again on the next pop-up window

That’s all there is to it, the drive will now format and erase everything on it.

Smaller external hard drives, SSD’s, and USB flash keys format quickly, while a larger hard drive may take a while longer. When completed, the drive will be formatted to the Mac OS X compatible HFS+ filesystem.

The videos below demonstrate the complete process of formatting an external hard drive for full Mac OS X compatibility, this uses the new Disk Utility in modern versions of OS X:

Similarly, you can perform the same type of process in OS X for making a USB flash drive compatible with Mac OS using the Disk Utility in OS X, as you can see, it’s a quick procedure that is done in short order on any Mac:

Should you intend to make an OS X installer drive or create any other bootable Mac OS X volume from a drive, or use a new drive as a fully compatible Time Machine backup drive, you will also need to complete this process.