There comes a time in every Mac user’s life when we need more space than is available on our machine’s startup disk. Even with the advent of cloud storage, adding that space usually means buying an external hard drive or SSD. And while you can buy external drives preformatted for Mac, they tend to be more expensive than those formatted for Windows. And there are fewer to choose from. So, it’s likely that the first thing you will need to do when you buy an external hard drive or SSD for your Mac is to reformat it. And while it’s pretty simple to reformat a drive using Disk Utility, there is one question you need to answer: what’s the best disk format for Mac? We’ll answer that question here.
What is a disk format on Mac?
Before we discuss the options for formatting a disk, it’s worth explaining what we mean by disk format. The term just means the way in which data on the disk is organized and indexed and the options available for manipulating it.
How to clear space on a disk
If your reason for buying and formatting an external disk is running out of space on your startup disk, you should try freeing up space first. One of the best ways to do that is to use a specialist tool that can track down system junk, identify the oldest and largest files, and uninstall applications. We recommend CleanMyMac. It can do all of those things and save you gigabytes or even tens of gigabytes of space on your boot disk. You might find you don’t need a new disk at all! You can download it for free here.
What disk formats are compatible with macOS?
While your Mac can read and write the FAT system used by older versions of Windows, and with the help of additional software, NTFS, too, it’s not recommended that you format a drive using either of those if you intend to use the drive mainly with a Mac. That’s because neither system is fully supported by macOS and the alternatives offer far more options.
The two native Mac file systems are APFS and HFS+. For years, from the first version of Mac OS X until macOS Sierra, HFS+, also known as macOS Extended (Journaled), was the default file system, and the only question was whether you used the standard format or the case-sensitive or encrypted versions.
Now, however, there’s a relatively new kid in town — APFS. Think of APFS as a modern, more flexible version of HFS+. It’s designed for SSDs but works just as well on mechanical hard drives.
Key features of APFS
- Snapshots
- Strong encryption
- Space sharing
- Fast directory sizing
One of the key features of APFS — and one of the reasons it has replaced Mac OS Extended — is that containers on an APFS-formatted disk can grow and shrink as needed. On a Mac OS Extended disk, when you create a partition, the size is fixed. The volumes on that partition are limited to the amount of space allocated to it when it was created. However, containers on an APFS disk, which are similar to partitions on Mac OS Extended disk, don’t have a fixed size. They can expand as needed to house the data stored on them. And when one container on a disk expands, another contracts.
Just like Mac’s hard drive, external drives can get cluttered and accumulate junk files. Luckily, there is an easy and automatic way to get rid of these unneeded files — Connected Devices tool that comes with CleanMyMac Menu. To access it, click a little iMac icon from the menu bar and navigate to the Connected Devices tab. There, you can see the volume of junk files on your external drive and safely remove it by hovering over Junk and clicking Clean Up. You can also see the largest files by clicking Organize. Free download here.
When to use each format
In most cases, you should use APFS when formatting an external disk. The only reason to format a disk as Mac OS Extended is if you plan to use it with a pre-Sierra version of macOS that doesn’t support APFS.
Which is the best format?
So, now that we’ve explained the differences between the two formats, which one is the best to use on an external drive on your Mac? Well, we can rule out FAT for the reasons we outlined earlier. That leaves Mac OS Extended (Journaled), also known as HFS+, and APFS. There are several reasons why APFS is a better format, not least its flexible container sizes and ability to create snapshots. However, it’s not compatible with every version of macOS. So, the best format for Mac external drive is APFS if you have a Mac running a version of macOS that supports it. If not, or if you plan to use the disk with a Mac that doesn’t support APFS, format the disk as Mac OS Extended (Journaled).
There are options within those two formats, namely Case Sensitive and Encrypted. For most people, these can be safely ignored. If you have a particular need for case sensitivity — for example, if you have a lot of folders with the same name with the only difference being that some names are uppercase and others lowercase — then use that option. And if you really need to protect data on a disk from prying eyes, using an encrypted format is a better option than using third-party software to protect it.
How to format a disk on Mac
- Plug the disk into your Mac.
- Go to Applications > Utilities and launch Disk Utility.
- Choose the external disk in the sidebar.
- Click Erase in the toolbar.
- Give the disk a name and choose your format.
- Click Erase.
The best format for external drive Mac will be connected to is dependent on the Mac itself. However, for most people, with a fairly recent Mac, the answer is APFS.
Frequently asked questions
What are disk formats?
The term format, as it applies to computer disks, describes the way data on that disk is stored and indexed.
What’s the best disk format for Mac?
In most cases, the best format for a disk you are going to use with a Mac is APFS.
How do I format a disk?
Follow the instructions above to launch Disk Utility and erase the disk. The process of erasing the disk also formats it.
