How to Format an External Hard Drive on Mac?

By Eileen | Posted to Home > Howto, updated on August 18th, 2021

Summary: Don't know how to format an external hard drive on mac? This article tells you how to erase external hard drives on Mac with the best format.

format external hard drive on Mac

"Format", a word which is connected with "all data clear" and which is different from what it is called so on Windows, has another name on Mac, "erase". Of course, there are different occasions where people want to get their external hard drives erased.

When there are bad sectors which don't store the data of bootstrap procedure, but of some important private files, people expect for formatting and backing up to make these files accessible again; when people's hard disks can no longer write in further, they expect for erasing disk to pave way for new items to write; when there are file system errors in people's hard disks resulting from frequent hot swapping, they expect for formatting to give rebirth to these dying disks and make them in use again.

Then how to format a external hard drive on Mac? Here are two methods for those people who urgently need to erase a external hard drive.

Part 1: Two methods to format external hard drive on Mac

Method I: Format an external hard drive through "Disk Utility" (newbie friendly)

Step 1: Connect the external hard drive with your Mac, and the computer will mount your external hard drive. Click here when external hard drive does't mount on Mac.

Step 2: Launchpad → Other → Disk Utility, and click the Disk Utility.

find disk utility

Step 3: Choose your target external hard drive or volume, click Erase on the top. If you find there's something wrong to read your external hard drive, then you can turn to external hard drive does't show up in Disk Utility for help.

enter disk utility

Step 4: Edit the disk name, select a format and a scheme.

start erasing disk

There are 10 formats (file systems) you can select in macOS 10.13 or above:

mac file system choose

And 3 kinds of Scheme you can choose:

GUID Partition Map: for all Intel-based Mac computers.

Master Boot Record: for Windows partitions that will be formatted as MS-DOS (FAT) or ExFAT.

Apple Partition Map: for compatibility with old PowerPC-based Mac computers.

Step 4: Click Erase to format your target disk.

finish erasing disk

Note: As for our example to erase a whole external hard drive, the original physical volume "X" and "Y" will have been deleted and a new volume "Untitled" will have been established. At that time, there will be an icon of your new-established volume on the desktop.

Step 5: Click Done, and congratulations that you have finished all the steps.

Steps to format a volume are 99% the same as that of a external hard drive.

erase volume

The most distinguishing difference of formatting between a volume and a external hard drive is that: if a external hard drive gets formatted, then all the volumes inside the external hard drive, which means all the data, will be deleted. Compared with that, if a volume gets formatted, only the one that gets formatted will be deleted, and that's to say, only the data of the formatted volume will be deleted.

Method II: Format an external hard drive through "Terminal"

Step 1: Launchpad → Other → Terminal, and click Terminal.

terminal interface

Step 2: Input "diskutil list", press Enter to list out all your disks.

diskutil list

Step 3: Input the "erase" command: diskutil erasedisk + new file system + new disk name + identifier.

terminal format disk

For example: to format the whole disk 2 to hfs+, then the operating command is:

diskutil erasedisk hfs+ TD disk2 

To format a single volume to hfs+, like disk2s1, then the operating command is:

diskutil erasedisk hfs+ TD disk2s1


1. There's no limitation of uppercase or lower case.

2. HFS+ can be replaced by other file system formats, and here provide some references like APFS, JHFS+, FAT32 and ExFAT.

3. "TD" is the name that I give to the new disk and it can be replaced by any word you like.

4. "disk 2" is the IDENTIFIER, or rather, the target disk that I want to format.

Well done! Finished erasing on disk2! Now I believe you have master another method to format your external hard drive. Take a try!

Well, if you find that you can't format your disk due to the loss of some fatal meta files, you are bound to stop to recover your data and the iBoysoft Data Recovery can help you find the lost meta files.

Part 2: Understand external hard drive, container, volume and partition on Mac

If you newly switch from Windows PC to Mac, you may get confused with external hard drive, partition, container, and volume in Disk Utility. Here are the differences.

disk container partition volume

External hard drive: external hard drive is the hardware component like HDD and SSD that you used to store the data. In Mac Disk Utility, it shows in the first line of the whole disk directory (e.g. disk2).

Partition: different from Windows, the partition is more like an operation to divide the entire, large, uncultivated, lonely, and original disk space. When you partition your external hard drive, the partition map is created when the external hard drive is erased and the partition map defines how and what the partitions should be. But on Mac, a partition can't be in effect unless it has been activated, i.e. being formatted with a file system. A partition with a file system will be called a volume on Mac.

partition mac

Container: Only the APFS has the Container where volumes share space with each other, which meanwhile implies that if one of the volumes is up to the entire partition capacity, there will be no space left for the other volumes to use in this partition. The Container is a special kind of partition on mac.

container mac

Volume: on Mac, any partition that is formatted with a file system before storing data is called a volume (e.g. disk2s1). Any available partition can divide its capacity into numerous volumes in a very easy-going way on mac while their names are editable. For an APFS external hard drive, APFS volume is a third-level unit of the storage device.

volume mac


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