Instructions: How to format an external hard drive on Mac

Formatting an external hard drive on the Apple Mac is no problem thanks to the hard drive utility. The only important thing is the correct settings such as format or file system and scheme. What you need to know about deleting and formatting a hard drive under macOS, I have put together for you in this guide. If you have a question in addition to the information shown and the step-by-step instructions, please write it as a comment under this post. The same applies of course to your experiences and reports on the topic;)

Why format an external hard drive on Apple Mac?

Before we get to the individual steps and give the hard drive a fresh format and free up space in the process, let's take a look at the reasons for doing this. For example, it could be that you buy a new external storage device, but it is more formatted for Microsoft Windows on the PC - for example with an NTFS system (see below). 

Do you want to use the storage medium primarily on the Apple Mac, iMac or MacBook, create corresponding partitions on it or install an installer on it, then it should be set for use on the Apple computer. The same applies to older disks that you want to renew when you switch from Windows to macOS or that you want to clear and set up for a current system without such a reason.

Open Disk Utility on macOS

It doesn't matter whether it's HDD hard drives with rotating magnetic disks or SSD memory with chips - with the Disk Utility on the Apple Mac you can manage storage media extensively. USB sticks and similar storage devices can also be managed with it. You can open the app from the folder at will Macintosh HD -> Program -> Utilities, über die Spotlight search (cmd + spacebar) or via the launchpad. Once this is done, you will find an overview of the storage installed in the Mac and connected via USB or other interfaces. Select the external hard drive that you want to format from the corresponding list (left).

Format external hard drive on Mac

If you click on the hard drive in question, you will see the details on the right of the storage media overview. The information is not too interesting, because formatting frees up the storage space and - if desired - assigns a new file system. To do this, click on in the upper toolbar Delete. 

You will then be shown menus from which you can e.g. B. can choose the format or file system and the scheme. In addition, you can enter the desired name of the memory in a text field. So that you don't despair when choosing the options from the drop-down menus, you will find an overview of the file systems and schemes below.

File formats and what they mean

Depending on the Mac OS, OS X and macOS version, you may be presented with a different selection of formats and schemes. Starting with macOS 10.13 High Sierra you will probably find the Apple File System (APFS) underneath. But there are also Mac OS Extended, MS-DOS (FAT or FAT32) and ExFAT. Here is an overview:

• APFS (Apple File System) - The latest file system made as a format for systems from macOS 10.13 onwards; is not compatible with Windows or Linux computers
• Mac OS Extended (Journaled, with or without upper / lower case, optionally with HFS +)  - The previous format for Apple computers, which you should select for Macs up to macOS 10.12; also not compatible with PCs
• ExFAT - The "Extended File Allocation Table" was introduced in 2006 for flash storage and is ideal for SSD storage that you want to use on both Mac and PC; We recommend maximum file sizes of up to 512 TB, theoretically up to 64 ZiB are possible
• MS-DOS file system (FAT32) - The MS-DOS format can be used with both the Apple Mac and Windows PCs and can therefore be used for data exchange between the two systems; FAT32 is the file system that was introduced for Windows 1996B in 95
• MS-DOS File System (FAT) - Obsolete file system (dating from 1977) that only supports small files and capacities (not recommended)

Choosing the right scheme

Depending on the hard drive or USB stick, it may happen that no schema selection is displayed at all. If this is the case, however, then you can use the following list as a guide in order not only to try out the schemes, but to select them specifically (selection may vary depending on the format):

• GUID Partition Table - Made for Intel-based Mac models; required for storage of 2 TB and larger; is designed for a maximum of 128 partitions
• Master Boot Record - For storage media with MS-DOS (FAT, FAT32 and ExFAT) that are less than 2 TB of storage space; limited to 4 partitions
• Apple Partition Map: Intended for older Macs that are PowerPC-based

More on this topic: Wiki article on partition tables

What about NTFS on the Mac?

NTFS is the format for hard disks that only runs under Windows. Apple computers with Mac OS, OS X or macOS can only read from this system, but cannot write anything to it. So if you use an external hard drive with an NTFS file system on your Mac, you can see the content, but you cannot change anything, edit files, add them or delete something.

To solve this problem, you can either format the hard drive (back up all files beforehand) or install third-party software that enables NTFS to be used. If you want to continue to use the external hard drive with PCs in addition to Macs, then it is best to format it (after a backup) in ExFAT format. 

Further information: Apple Support Document HT208496

Jen Kleinholz( Founder & Sir Apfelot )

Jens has been running the blog since 2012. He acts as Sir Apfelot for his readers and helps them with technical problems. In his spare time he rides electric unicycles, takes photos (preferably with the iPhone, of course), climbs around in the Hessian mountains or hikes with the family. His articles deal with Apple products, news from the world of drones or solutions to current bugs.