Format External Hard Drive Title Image 2

You’re right. You can use any external hard drive on a Mac.

And that means you have a lot of choices in choosing a brand.

And of the price point that suits you when you buy an external hard drive for your Mac.

And once you have your external hard drive, if it’s not in a ‘For Mac’ format already.

No issue you can quickly and simply format your external hard drive for your Mac.

Format Your External Hard Drive To Use On Your Mac

Here is a quick overview. It’ll give you a feel for what you’re going to learn.

1. Log into your Mac. And plug your external hard drive into your Mac

2. Start Disk Utility. To do this, open a Finder window. Click on Applications folder. Then the Utilities folder. Click on Disk Utility.

3. Under ‘External’ on the left hand side of the window. Click on your external hard drive. Then click Erase at the top of the Disk Utility window.

4. Type in a Name. Choose the format Mac OS Extended File System. Scheme is GUID Partition Map. Then click Erase.

Now have a look at formatting an external hard drive for Mac in more detail.

Since the Mac OS update 10.13 released in October 2017, there are just a couple of things for you to watch for.

Format External Hard Drive For Mac

When you format your external hard drive for your Mac to use, you use software called Disk Utility.

There’s no software to buy as this program is a standard part of your Mac’s operating system.

A Side Note For You:

Formatting or reformatting your external hard for your Mac means you’ll lose any files on the drive.

A good example is, if you know that files are on there from a Windows PC. Or you know that your external hard drive comes with Windows PC software on it. And you’ll want to use that software, copy those files off.

If you’d prefer not to reformat your external hard drive. Then read my article “External Hard Drive Compatible with Mac & PC without Reformatting” to find out how to do that.

You’re now ready to start.

1. Start Up Your Mac And Log In.

Check your MacBook Pro or MacBook Air is charged up or connected to power.  Particularly if your external hard drive is one powered by its USB cable. The last thing you want is your Mac’s power running out part way through formatting.

2. Plug In Your External Hard Drive.

Your drive will have a USB A or Thunderbolt (USB C) or even a Firewire plug for you to plug into your Mac.

You may have an external hard drive with a USB type A plug on the end of its USB cable.

USB A Cable End
USB Type A Cable End

And if your Mac only has USB C ports then you’ll need an adaptor cable to plug in.

USB C Cable End
USB C Cable End

You can find out more about this in an article on the site “Connect an External Hard Drive to Mac, 12 things You Need to Know“. You can follow this link to take a look.

Your external hard drive connected up? You should now see your drive icon on your desktop.  It’ll look something like this.

New Drive Icon On Desktop
New Drive Icon On Desktop

No drive icon?

Try this.

Open up a Finder Window and click on finder preferences.

Finder Preferences
Finder Preferences

On the General Tab, check that the ‘External Drive’ box is checked.

Finder Preferences Show External Disks
Finder Preferences Show External Disks

This setting tells your Mac to show your drive icon on your desktop.

3. Open Disk Utility.

You can start up Disk Utility from a Finder Window.

Click on your Application’s Folder. Then click on Utilities inside your Application’s folder

Finder Application Folder Utilities
Finder Application Folder Utilities

Inside the Utilities folder you’ll find Disk Utility.

Finder Disk Utility
Finder Disk Utility

Click on Disk Utility to start it up.

4. In Disk Utility

Look to the left hand side of your Disk Utility pop up window.

On that side of the screen you’ll see a list. Your internal drive at the top. And your external drive underneath.

Right under the ‘External” heading is where you’ll find your external hard drive.

Format Internal External drive list
Format Internal External drive list

Click to choose your new external hard drive under the external heading.

The red arrow in the picture above shows you where.

Take care to click on your drive at the right level.

At the top of the hierarchy. Where the red arrow points.

Picking your external hard drive at a lower level will give you all sorts of problems. Including not being able to format.

And later if you want to partition your external hard drive you’ll have issues.

Can’t see the drive levels? Or there is only one level?

Click on the arrow to the left of your drive to show you the levels.

Did that work?


Look to the top of your Disk Utility pop up window. For the ‘View’ option. It hides a drop down menu.

Disk Utility View Option
Disk Utility View Option

Click on the down arrow to open and choose to see all the devices on your Mac.  The drive and the volume.

Is your hard drive chosen and at the right level?

Good you can go on.

5. Click Erase At The Top Of The Disk Utility Pop Up Window.

You’ll see a few options across the top of the Disk Utility screen.

Select the erase option.

Select Erase
Select Erase

Don’t worry, you’re not erasing anything right now. You’ll need to set up a few things on your Mac Disk Utility screen first.

On your next Disk Utility pop up window you type in your settings for the formatting of your drive.

Format Format Pop Up Window
Format Pop Up Window

6. Put In Your Settings For The Format Of Your External Hard Drive For Your Mac.

Give your external hard drive a name. 

You’ll find it easier later to pick name that makes it easy to find your external hard drive on your Mac’s desktop. And one that gives you a clue about what you’re using your hard drive for.

Underneath the name you’ll set the format. This is the format you want for your external hard drive on your Mac.

Choose Mac OS Extended (Journaled) file system as the format.

Mac OS Extended (Journaled) file system is the file system format you want for your Mac.  It allows you to copy and paste from your Mac to your external hard drive.

Drag and drop your files to your external hard drive.

And use your external hard drive for your Mac’s Time Machine backup.

Pick GUID Partition Map for the scheme.

This is important too. Your Mac needs the GUID Partition Map scheme. Or you’ll have all sorts of odd problems using your drive later on your Mac.

And when your reformatting a Windows PC formatted external drive. Their scheme is different. And you must change it to GUID Partition Map for your Mac.

The red arrows in the picture show you where you can find the format and scheme list of options.

7. Click On Erase.

Now you select the Erase button.

Your Mac will take a few minutes to format your external hard drive.  And once done your external drive is ready for you to use.

You can then dismiss the Disk Utility screen.

8. Your External Hard Drive Is Formatted On Your Mac.

Hooray? Once formatted you can use your external drive just as you would a USB stick. But of course your external hard drive is way bigger.

Your external hard drive will show up on your Mac’s desktop.

You’ll see it with the name you’ve given it. And it’s all ready for you to use.

And when you’re ready to pack the drive away be sure to Eject your Drive.

Right Click to Eject
Right Click to Eject

Quick 3 Minute 18 Second YouTube Video

Would you like to see a video run through?

This quick 3 minute video runs through how you format your external hard drive for Mac.  Enjoy.

How to Format an External Drive for Mac

Video Credit Flavio D

Format External Hard Drive For Mac Frequently Asked Questions

1. Why Format An External Hard Drive For Mac?

Because when you’ve bought a hard drive and found it’s read only. Or you know right up front that it’s ‘not for a Mac’. You need to format it.

Most external hard drives are marketed for Windows PC’s.

And they’re in a format called NTFS.

Your Mac can read an NTFS drive. But you won’t be able to copy any files onto an NTFS drive. Or change any files on an NTFS drive. Unless you either use special software. Or format the drive for your Mac.

The great thing about your Mac is that it’ll use any external drive out there. As long as it’s in the right format.

2. The Best Format For An External Hard Drive On Your Mac

The best format to copy and paste to or to use for a Time Machine backup Is Mac OS Extended (Journaled) file system.

This file system is also known as HFS+

I am assuming here that you have a mechanical external hard drive and not an SSD drive.

This is the file system to choose if you’re only using your external hard drive on your Mac. There are other options you can format your external hard drive to. And what you choose depends on the type of drive and what you plan to use it for.

APFS is another file system that newer Macs use. It’s aimed at Solid State Drives – SSD’s.

Right now it only works on SSD’s and Flash drives. And APFS is not compatible with Time Machine.

With the price of SSD’s per TB of storage so much higher than mechanical portable external drives. It’s more cost efficient to buy and use an external hard drive for backup.

Unless money is no object and you need an ultra fast backup.

3. What Is The Best Format For An External Hard Drive On Mac For Time Machine

Want to use your shiny new external hard drive for Time Machine? You’ll need to format it to Mac OS Extended File system.

And if you want to know how to hook up your new external hard drive to Time Machine. Read my article on the site here.

In a few more steps you’ll have that all set up too.

4. I Click On Erase And Get An Error

Erase Process Failed
Erase Process Failed

Check you have selected your external hard drive at the top level in Disk Utility. And before going to your formatting options screen.

Format Internal External drive list
Format Internal External drive list

If you have. Check your drive.

Click on ‘First Aid’ at the top of your Disk Utility window. Run a check on your external hard drive to make sure all is well with it.

5. What If You Want To Format Your External Drive As APFS (Apple File System)?

Or if your external drive is APFS formatted.

APFS is a file system introduced by Apple with High Sierra.

It’s made to be faster and more efficient. And is particularly designed for solid state disks (SSD’s). You won’t be able to format a mechanical (hard) drive as APFS.

APFS does not support Time Machine.

So if you want to use your SSD drive for your Time Machine backup on your Mac. You’ll need to format your SSD drive as Mac OS Extended (Journaled) file system.

But if you want to use your SSD external hard drive as a boot drive. Or to copy and paste files to and from. Then you can pick APFS from the available formatting options in the Erase screen of Disk Utility.

YouTube Video External Hard Drive Setup On A Mac Mojave

You’ll find here a YouTube video by Tech and Design. It’s 11 minutes 36 second long. So not as quick a run through as the video above.

He uses the Mac operating system Mojave. And I think you’ll find the video is aimed at the more technical. And those who would like to format a shareable drive as well as a drive for Mac.

How To Format Your External Hard Drive In MacOS Mojave | Set Up To work On Mac

Video Credit: Tech & Design

Last Words

And now you have your external hard drive formatted for your Mac.

If you’d like to now partition your external hard drive.

Not sure what partitioning is?

It’s about taking a large external hard drive and making separate areas. Areas that you can use for different things. For example you could have an area that you copy and paste to.

Then a separate area you use for your Time Machine backup.

And you may even create a third area to share between your Mac and a Windows PC.

You’ll find an article that shows you how to do it right here.

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External drive for Mac and PC with Files Interchangeable


  1. Hey folks: thanks for the helpful suggestions about how to activate my new external hard drive from Seagate. Much appreciated.

    1. Hi Bill, You’re welcome. I’m glad that you found the post helpful. Your comment is much appreciated.

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