How to Format External Memory/ Media Devices Using A Mac

Formatting USB Drives, SD Cards, Micro-SD Cards, and External Hard Drives using Mac

The steps that follow should format all of the listed external memory devices (Plus any I may have overlooked)

Step 1:

Insert your drive into an empty port. (i.e. USB port, SD port, or external card reader)

Important Note: After the drive mounts ensure you take note of the name of the drive, as you will need this information later.


Step 2:

Finder>Applications>Utilities>Disk Utility


Navigate to the Disk Utility application. To do this, open a new Finder window. Click on the Applications tab on the left side of the window. Scroll down to the Utilities folder. Locate the Disk Utility application and double click to open.


Step 3:


When the Disk Utility application opens, locate the inserted drive by name on the left hand side of the application. When located, click the name and this will show you the particulars of the drive. (i.e. The amount of memory that is currently used, the capacity of the drive, etc.)

Step 4:


Once you’ve selected the drive, there will be numerous options of tasks you can complete from this point, which will be located along the top half of the application. These include First Aid, Partition, Erase, Unmount, and Info. For our current purposes, select the Erase option. When you’ve selected the Erase option, a new window will open and will offer more options that will include naming the drive, formatting options, and partition schemes.


Step 5:

Choose a name for your drive. I like to name my drives differently, as I commonly have numerous drives plugged in at once. But if it is all the same to you, you can just leave the current name of the drive.


Step 6:

Select what format you want the drive to be. There should be 4 options in a drop down menu for you to choose from. These should include OS X Extended (Journaled), OS X Extended (Case-sensitive, Journaled), MS-DOS (FAT), and ExFat. For everyday use, you can leave the partition scheme alone.

Depending on what your intentions of use are with the drive after formatting, you will need to select the correct format to use.

  • OS X Extended (Journaled) is simply the default format for the drive to be used with computers using a mac operating system. It also allows for faster file recovery if the drive is to fail for some reason.
  • OS X Extended (Case-sensitive, Journaled) is essentially the same, but when saving files in directories the upper or lower case letters used in the name of files is taken into account. (Ie. FileName.dmg and Filename.dmg can be saved in the same directory without conflict).
  • MS-DOS (FAT) is a Mac and Windows operating system compatible format, to an extent. MS-DOS (FAT) – otherwise known as FAT32 in a windows format – can only transfer files that are 4Gb in size or less.
  • And finally, the ExFAT format is completely compatible with Mac and Windows operating systems, with no file size limit. This is essentially the most versatile of the formatting options.

More information on the uses of specific formats can be found here.


Important Note: When erasing different types of media, you will sometimes see added or subtractted formats, most of these will be for encryption purposes. This will depend on what the drive was formatted to prior to the current formatting (Eg. If it was formatted to a Master Boot Record scheme, it will have less format options).



Step 7:


Click Erase! A new window will open as the drive is being formatted. Depending on what settings you’ve selected (Format and Security) the formatting process will vary in time. And that’s it! Once the format is complete, you can use your drive for whatever purpose you intended!


All the best,



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