How to Select an External Hard Drive for macOS Time Machine Backups

Time Machine backups are a reliable option for backing up your Mac. But which hard drives should you pair with macOS’ built-in backup app? Here’s how to select the best backup disk for your needs.

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Time Machine is a proven macOS backup solution. The only issues are that you need a hard drive or two and have to remember to physically connect an external drive to your Mac. I found that using a docking station, both at work and at home, solved these issues.

But which external hard drive should you use to collect Time Machine backups? Although many options exist, some will work better than others depending on your preferences. Here’s how to select the best external hard drive for Time Machine backups.

How to Select an External Hard Drive for macOS Time Machine Backups

Form factor

One of the first questions to ask yourself is whether you need a full-size external hard drive that requires its own power source. An example of such an option, sometimes referred to as a desktop player, is SanDisk’s G-DRIVE.

In my experience, however, external drives that require their own independent power source fall out of favor. Instead, portable offerings such as My Passport for Mac from Western Digital (Figure A) and Seagate Basic Portable Drive are increasingly popular, in part due to their flexibility and ease of transport.

Figure A

Western Digital’s My Passport for Mac is a budget-friendly external hard drive well suited for collecting Time Machine backups.


Another issue to address is the storage capacity of the external hard drive. While 1TB was enough to collect a long history of Time Machine backups, some newer Macs come with built-in drives of this size.

A good rule of thumb is to purchase an external backup drive at least three times the size of the Mac’s own drive. If your Mac uses a 256GB SSD, a 1TB external drive should work well for collecting Time Machine backups. But if your Mac uses a 1TB drive, consider buying a 3TB or 4TB external drive. Fortunately, prices have dropped to the point that a reliable 4TB drive can usually be had for around $150.

Connection method

Before buying an external hard drive for the purpose of collecting Time Machine backups, be sure to review the way you work. If your typical workday involves connecting a power cable and an external monitor to your Mac, and your Mac only has two Thunderbolt/USB-C ports, you’ll need to consider a docking station or hub such as Twelve South StayGo USB-C Hub Where Brydge’s Stone C Model.

Or maybe your Mac has a free Thunderbolt/USB-C port, or you’re using a third-party docking station that offers traditional USB-A ports. When buying an external hard drive to store Time Machine backups, first confirm that the drive has the connectivity option you need. If you have a choice, consider converting to Thunderbolt/USB-C, as the standard offers faster data throughput and can speed up backup operations.


While some discs come in the form of thin and elegant shells, the LaCie Mobile Drive is an example – offering minimal protection against drops, shocks and vibrations common when traveling, others are more suitable for rugged application. LaCie Rugged Portable Hard Drive (Figure B) is such an example, and one that I have personally found, over the years, works well in the field.

Figure B

The LaCie Rugged Portable Hard Drive comes in a variety of storage capacities, features a rubberized shell, and is designed for mobile use.

Consider your needs, then explore the multitude of offers available. Just be sure to consider the benefits of a rugged or rubberized shell which can help extend the life of the drive if you need the drive to be highly mobile.


External hard drive performance impacts how quickly Time Machine backups can be performed. Several factors come into play, including the type of hard drive and the speed of the Mac. For example, SSDs in newer MacBook Pros with faster M2 chips and high-performance backplanes will automatically have an advantage over an older iMac with a traditional 5400 RPM hard drive.

But the type of external hard drive and its connection method will also impact the backup time. An external SSD drive will perform faster than a traditional 5400 RPM equipped drive. And as noted earlier, Thunderbolt connections are generally able to transfer data faster than older USB-A connections.

Buy from trusted vendors

Once you’ve made your decision, be sure to buy from a trusted supplier. I recommend avoiding buying second-hand external hard drives and not trusting all online vendors. Instead, consider purchasing external hard drives directly from Apple or the respective hardware manufacturer.

Shirlene J. Manley