Introduction to Reformatting a USB or HDD on MacOS

Reformatting a USB or HDD on MacOS is a simple and quick tutorial that will help you reformat a USB drive or external HDD on MacOS. There are many versions of MacOS and some parts may be slightly different. The app “Disk Utility” generally has not changed for a number of years on MacOS or Mac OSX as it was previously known.

To reformat a USB or HDD on MacOS you will need to first insert the USB or external HDD into the Mac and wait for it to initialise or load as normal. This step will depend on if your USB or HDD has data on it and was thus formatted before, or if it was bought new and needs to be formatted for the first time.


The quickest way to launch Disk Utility is to search for it in Spotlight and type Disk Utility. The app will likely come up even before you finish typing. You can alternatively launch it from Application > Utilities and then selecting the Disk Utility app icon.

Once you have clicked and launched the app, it will display a screen somewhat similar to this:

Opening the Disk Utility app will greet you with this screen. Showing you your main HDD.

In MacOS, reformat is named “Erase”. You will see this option on the tool bar at the top of Disk Utility or by right clicking the Hard Drive on the sidebar in the Disk Utility window.

You will notice that some options will be disabled for the primary hard drive. This is due to it containing your operating system and its only possible to erase that drive when in recovery modes.

Choosing Formats and Partitions

Selecting “Erase” will present you with a dialogue box that will ask you to rename the USB drive or HDD. a format you wish to establish for the device and also a partition table.

The name is pretty self explanatory, it is what will show when you plug in the device into any device or computer. The Format is the most important element of a format or reformatting. It will dictate on which devices it will be able to work as intended, how big files can be and even how you may name your USB or HDD.

I will give you a list below of different benefits and advantages to each format that the latest version will present you. The list is by no means complete but will cover the primary formats that MacOS will provide without extra software being installed.


Robert Mizen is a Producer, Tech Consultant and all things nerdy person. Interested in Games, Apps, Web, Green Tech, Astrophysics and Travel. This website is a outlet to express so i dont explode.


Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.