How to Reformat Mac External Hard Drive

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Is your Mac acting up? Perhaps it’s in dire need of releasing some data to an external backup drive. This is where Mac reformat external hard drive might help!

Just like the human body, your computer can have sand in its machinery throughout its running course and end up crashing everything.

Factors that contribute to this include viruses, extensive data, wear and tear, and program malfunctions that can inflict system problems.

Alright, you want to move your important data on Mac to the external backup space, but it seems like prior reformatting is needed.

You probably think twice about doing some formatting, considering how its meaning is associated as file reset and full wipe. Reformatting, however, is one of the safest and most guaranteed ways to help your computer system smooth again, to say the least.

Before getting to the procedure of Mac reformat external hard drive, though, it’s essential to understand when and why you should attempt formatting, too. This article will also highlight Mac repartition external hard drive that can help you manage file storage effectively.

Mac reformat external hard drive: when?

If you stick loyally to a computer older than your almost-teenage sibling, then we got your answer on a postcard: you should’ve done it already if you haven’t.

Let us refresh your checklist: have you scanned it for virus and clean any spotted ones? Is it possible that it’s infected with spyware? Did you ever perform an incomplete or unsuccessful defragmenting on your computer? 

If you have done these and not meet desired results, do know that all is not lost. It’s probably already the time for some reformatting, even more so if your computer is as slow as molasses in January.

Mac reformat external hard drive: why?

A slow computer is always the most annoying problem, not to mention the crashed system, registry errors, and possible malware after all that Internet streaming.

It’s better to keep your important data safe while you’re fixing these problems separately, which is why your external hard drive should be ready to use. 

For those purchasing a new external drive, many also suggest to format it first before using, since there might be extra software and files inside that might not be useful to you or even harmful. Besides reassuring you of this concern, formatting it will give more space you probably need.

A girl connecting an external hard drive to her Macbook
A girl connecting an external hard drive to her Macbook

There’s also another reason why formatting before using is strongly advised when you purchased a new portable SSD or external hard drive. You’ll see that once you plug it in, your macOS reject your request to write or put some data to the drive.

It’s in no way an error from your Mac or purchased product: most external hard drives are initiated with Windows NT File System (NTFS), which obviously doesn’t support Mac from Apple.

Unless you download a purchased app named Paragon NTFS for Mac, the only way to befriend the drive with your Mac is by changing the format.

In a bit, we’ll tell you how to format your drive, but you should know first that formatting it to Mac OS Extended (Journaled) will keep you from reckoning without its host and finally allow you to use the drive you purchased.

Let’s take the most popular external drive example: 1 TB Seagate Expansion.

If you attach it to your Mac right after pulling off the cases, you’ll see its default contents, including a folder with Seagate blue logo titled “Start_Here-Mac” (since you obviously use Mac).

You’ll be directed to one particular page on the Seagate website afterward, which informs you that the drive is set up to work with a Windows laptop or computer instead (NTFS format).

If you’re not connected to the internet, you can try right-clicking the icon of the drive on the desktop before clicking on “Get Info.” Voila, you solve the puzzle: it’s formatted as Windows NT File System (NTFS) in default.

It’s a foregone conclusion that reformatting the drive is the only way for Mac users.

Mac reformat external hard drive: how?

We now know that you’re already sure to reformat your Mac hard drive, considering you’re reaching this part.

Doing Mac reformat external hard drive isn’t as complicated as you might think in the first place.

Disk Utility app in Mac OS (

There are only several quick steps to go, and you’ll get your backup files as well as a healthy system and finally make peace with the world.

  1. Shut down your Mac first before plugging in the drive you want to reformat. It can be either a USB drive or an external drive, and this step is the same for both desktops and laptops.
  2. Power your Mac up.
  3. Go to the “Finder” folder to allow the drive to be mounted on the desktop by ticking “Show These Items on the Desktop” for your “External Disk.”
  4. Make sure to double-check for any data you wish to store before reformatting. You can either move them onto internal Mac’s drive or uploading them to Cloud storage. Don’t interrupt this process by ensuring your computer still has power left or connected to the electrical outlet.
  5. Now all preparation is ready, go to the “Applications” folder > “Utilities” sub-folder > “Disk Utility” application.
  6. Locate your external drive icon or name from the left section, before clicking on the “Erase” tab at the top of the prompt box.
  7. An automatic prompt will appear and ask you to choose the intended format you wish to conduct. The most common and recommended one is Mac OS Extended (Journaled) file system (and we’ll explain more after this), but you can also select “MS-DOS (FAT)” or “ExFAT” if your drive is to be used in Mac and Windows (both still have its difference, though). Here, you can choose to change the name of your external drive, too.
  8. This is your last chance to confirm your drive formatting, which means you already comprehend that any data on it will be deleted altogether. Else, go ahead if you’re already sure.
  9. Let the disk to do its formatting (this should be done in less than one minute).
  10. Once done, you can go back to the drive row in “Finder” and notice all information and partitions are erased, leaving you with a clean space to put new data. Do a final check to ensure the procedure is successful by clicking “Get Info” on the drive icon. You’ll see its name changed to “Mac OS Extended (Journaled)” from “Windows NT File System (NTFS).” Feel free to begin adding files or patch it up as your new backup option with Time Machine, if you wish so.

Mac OS Extended (Journaled) is a particular file system from Apple, and sometimes they’re also referred to as HFS Plus.

This feature is added along with the launch of Mac OS X 10.2.2 29 back on November 11, 2002, to enhance users’ data reliability.

Each formatting will determine how your files are saved on the hard disk. Mac OS Extended (Journaled) option is the most normal for both internal and external drive, particularly if you’re going to use it solely on your Mac or considering utilizing Time Machine backup, which only works with a Mac OS-formatted drive.

Mac repartition external hard drive: how?

We share your annoyance when our computer multitasking ends up hindering any work progress.

It’s where Mac repartition external hard drive comes: repartitioning the disk is an excellent decision when running two operating systems at the same time on the same Mac.

Partition in Mac OS Disk Utility app
Partition in Mac OS Disk Utility app (

It’s just as easy as Mac reformat external hard drive:

  1. Return to “Disk Utility” and click on your external drive right under “External” since the other words below it will be unclickable
  2. Click “Partition” on the top of the prompt box
  3. Another box will come out to show you the figure of the external drive, of which you can adjust each desired partition size.
  4. Name the partitions and set up a file system for each before clicking “Apply.”
  5. Another prompt box will appear, asking you whether to “Partition” or to “Cancel.”
  6. Once the procedure is done, you can go to the desktop to check for any disk icon befitting each partition you have made earlier.

Final Thoughts

Computer users mostly neglect or forget the importance of doing regular reformatting and repartitioning, thus resulting in their device encountering errors after that.

In some worse cases, users may encounter corrupted-beyond-repair data and missing files, upon which every fix attempt might have failed miserably.

Now that you have known the steps for reformatting and repartitioning, you can finally rest assured knowing your computer has a higher chance of keeping its superb system performance—an appeal that can pique any computer users’ interest!

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