With Mac hard drives becoming increasingly difficult and expensive to upgrade internally, an external hard drive provides the perfect solution.

However, the technology of external hard drives and the connection port types on Macs have changed a lot in the past few years so it can be quite confusing knowing what to go for, and how to to use them with Macs.

Going for the cheapest hard drives with the most storage space is definitely a false economy in our experience and the loss of your precious data can be priceless.

The best external hard drives for Mac users fulfill similar criteria to those that are best for PCs but there are some specific things that make some more Mac compatible than others.

Here then are some essential points to consider when buying and using an external hard drive on Mac to help you decide which one is best for you.

Please note that MacHow2 may sometimes earn compensation from clicks.

1. Reliability

Reliability is probably the most important consideration when purchasing an external hard drive for your Mac.

The worse thing that can happen to an external storage device is disk failure.

When this happens, you’ve usually lost everything stored on it which can be a total disaster if you’ve got precious family photos or important documents on there.

Manufacturers rate the reliability of their hard drives with “Annualized Failure Rates“. However, these figures should be taken with a pinch of salt.

Although manufacturers sometimes quote an Annualized Failure Rates of less than 1% (AFR is a percentage of total hard drives sold that fail annually) any figures on reliability aren’t worth basing your decision on in our opinion because everyone uses hard drives in different ways.

external hard drive mac annualized failure rates

For example, those that leave their external hard drives switched on all the time or use it constantly for video editing are going to experience more frequent failures than those that only switch them on occasionally for backups.

Most manufacturers will guarantee at least two years of reliability and the best manufacturers like Western Digital (WD) offer 3 years and OWC offer five year guarantees although in reality, all external hard drives should outlast this with moderate use.

Of course, any such guarantees are little compensation in terms of your precious data in the case of failure. You will have lost all of your files anyway but at least you’ll get a free replacement from the manufacturer.

If you want to learn more about why hard drives fail, you can find an interesting look at hard drive reliability here.

2. Buy A Decent Brand

This is probably the most important piece of advice when buying an external hard drive.

There is definitely a difference between established brands and lesser known newcomers to the market.

In 2019, the general consumer external hard drive market is dominated by two big players – Western Digital and Seagate – both of which have been in the business over 20 years.

At MacHow2, we use Western Digital (WD) external hard drives on a regular basis and would not hesitate to recommend them such as the extremely reliable WD My Passport range of external hard drives.

Note that Hitachi drives are now owned by Western Digital so if you buy a Hitachi external hard drive, you’re effectively getting a Western Digital product.

There are other brands such as LaCie, Fujitsu and Toshiba but they’re considerably behind the big two when it comes to external hard drive market share and reputation.

3. Schedule Backups & Usage

Do not use your external hard drive more than is absolutely necessary.

If you have it switched on all day, and particularly if you keep accessing it all day, it’s going to burn out far more quickly than if you just switch it on once daily or weekly to make backups.

Quite simply, the more you use an external hard drive, the quicker it will eventually fail.

Those that edit video on their Mac directly from an external drive can therefore expect their hard drive fail quicker and should definitely invest in higher end quality hard drives featured here such as the WD My Book Thunderbolt Duo or OWC ThunderBay.

4. Use A Second Backup Solution

If you’re using an external hard drive on your Mac for performing backups, you should consider using a second backup solution.

The chances of two external hard drives failing at the same moment are extremely slim so if your backups are really important, using two drives is the best thing you can do for backups.

If you don’t want to purchase a second drive, alternatively you can make sure you’re using a cloud backup solution in tandem with your external hard drive.

The WD My Book Duo for example also allows you to backup to it’s own Cloud service Western Digital MyCloud although this of course costs extra.

For Mac and iOS users however, the easiest solution is to backup using Apple’s iCloud alongside your external hard drive.

You get 5GB of free online storage with iCloud with plans starting at just $0.99 per month for 50GB.

5. Get A Power Surge Protector

One thing that can instantly destroy your hard drive is a power surge in your home or office electricity supply.

However, you can easily protect against this with a cheap Surge Protector Power Strip which is well worth the investment (for your Mac too).

what to look for external hard drive - surge protector

Note that a common occurrence with cheaper brand external hard drives is that the inverter inside fails which basically allows too much power to short-circuit and destroy the hard drive.

In these cases, a surge protector won’t help you which is another reason why we only recommend buying an external hard drive from a reputable brand.

6. Never Move A Drive When Its Switched On

Try never to move an external hard drive when it is switched on.

External hard drives have moving parts which read the magnetic surface of the drive.

There is a danger that the read/write heads can move and make contact with the hard drive in which case, it will break immediately.

The only way to avoid this is to buy a Solid State Drive (SSD) which has no moving parts although there are more expensive and have less storage capacity although this is slowly changing as the technology advances.

The internal hard drive on all new Macs are SSD drives which is why it’s perfectly safe to carry around a MacBook and not worry about damage from movement.

7. Buy The Most Storage Space You Can Afford

External hard drives now offer massive amounts of storage space and the starting point in most external hard drives is now generally at least 1 Terabyte or more.

1 TB equals 1000GB and is roughly equivalent to 488,000 photos and 220 full length movies so a 5TB hard drive could be enough for a lifetime of photos or music for most people (see the table below).storage comparison table

There’s no right or wrong answer when it asking yourself “how much storage storage space do I need?”. But our advice is simply to buy the biggest you can afford.

Cloud storage solutions such as iCloud and OneDrive are certainly reducing the need for physical storage but the bigger your external storage device is, the more it can grow with you.

As photos and videos increase in size (most high-end digital cameras and even iPhones can film in 4K for example which eats massive amounts of hard drive space) the bigger the better.

Nowadays, 1TB of hard drive can cost less than $100 while one of the biggest consumer priced external hard drives, the WD My Book Duo 20TB, costs around $700.

For those looking for serious storage space for enterprise backups or 4K video editing, the OWC ThunderBay goes up to 56TB but will set you back over a few thousand dollars.

8. Desktop vs Portable

There are two types of external hard drives for Mac: 3.5 inch desktop drives that have their own mains power source and 2.5 inch portable external drives that take their power from your Mac.

Portable drives will easily fit in your jacket pocket. At the moment, desktop drives go up to a maximum of around 56TB and Portable go to around 5TB.

Some of the biggest desktop external drives such as the WD My Book Duo and OWC ThunderBay are actually a combination of 2 drives in one enclosure which can be used as RAID (Redundant Array of Independent Disks) drives.

This basically means you can combine them both for double the speed, storage and performance.

9. SSD vs Mechanical Drives

Almost all external hard drives nowadays are still mechanical drives which means they have moving parts inside.

Mechanical external hard drives feature moving parts which can deteriorate and break more easily.

Solid State Drives have no moving parts, are therefore less likely to break and they’re incredibly fast but there are less available and are expensive for the little storage space they offer.

There’s no doubt that SSD drives will eventually replace mechanical drives in the external hard drive market but the economies of scale still aren’t there yet.

mechanical drive

A mechanical external hard drive.

All new Macs since 2012 (except iMacs, Mac Minis and non-retina MacBook Pros) have internal SSD hard drives fitted as standard and anyone that’s used older Macs with mechanical internal hard drives will tell you how much faster and efficient SSD drives are.

SSD drives are also silent and run cooler compared to mechanical drives which whir and buzz due to the drive spinning which also creates more heat.


A Solid State Drive (SSD)

There are also some hybrid drives that are a mix of solid state and SSD drives although these are less common.

As the technology improves, prices come down and capacity of SSD increases, it’s likely that eventually all external hard drives will be SSD drives.

But at the moment, mechanical drives still rule the external drive market and offer the biggest capacities for the best prices.

Currently, we rate the best SSD external hard drive for Mac as the Samsung T5 Portable but you only get 2TB and the list price is $479.99.

10. External Hard Drive Speeds

The speed of backups or data transfer from your Mac to your hard drive depends on two things – the connection port type (see below) and the hard drive’s physical speed denoted in Revolutions per Minute (RPM).

Most external hard drives are 5400RPM but there are some faster high-end drives that are 7200RPM.

A 7200RPM drive will be faster than a 5400RPM drive because the drive revolves faster and therefore can be read by the drive head quicker.

If you’re connecting a 7200RPM hard drive via a super fast Thunderbolt or USB 3.0 connection, then you’ll enjoy the hard drive’s maximum transfer speed.

However, a 7200RPM mechanical drive can’t achieve anything near Thunderbolt 3 speeds. A good example is the G-Tech Thunderbolt 3 external drive which has a 7200RPM mechanical drive but still can’t achieve the maximum transfer speed of Thunderbolt 3.

The G-Tech 2TB Mobile SSD can however because it’s a Solid State Drive (SSD).

All new Macs have Thunderbolt ports although the number of external hard drives that can take advantage of Thunderbolt speeds is still relatively small.

However, if you’re connecting with an older Mac via a USB 2.0 or Firewire port, then your connection cable won’t even be able to deliver the maximum speed of the hard drive so you might as well save some money and get a 5400RPM with greater capacity than a fast drive with less capacity.

The reality is that whichever hard drive you get, you’ll probably get around 100-200 Mbps transfer speed from most mechanical drives and about double this from an SSD drive.

This is well below the capabilities of most modern connection ports and cables but as we’ll explain shortly, external hard drive technology still hasn’t fully caught up with them.

Our advice is don’t worry too much about hard drive speed on external drives.

Most external hard drives have a USB 3.0 connection which will deliver incredibly fast transfer speeds. Most consumer priced external drives are 5400RPM anyway so it’s not something you can easily be choosy about.

7200RPM external drives tend to be more expensive, noisier and most manufacturers are concentrating on trying to deliver more speed by designing hard drives that can take full advantage of connection types, than hard drive speeds as we’ll see below.

11. Connection Port Types

The business of external hard drive connections can be extremely confusing as technology changes and Apple seemingly keeps changing ports on every new generation of Mac.

All new Macs since 2012 have ditched Firewire in favor of Thunderbolt 3 connections offering staggering maximum data transfer speeds of up to 40 Gigabits per second (Gbps). Port connection speeds are measured in “Megabits per second” (Mbps) or “Gigabits per second” (Gbps). 1000 Mbps equals 1 Gbps.

However, the problem is that most external hard drives don’t even support the transfer rates of the latest generation of Thunderbolt yet (Thunderbolt 3).

There are some SSD drives however that now do such as the G-Tech G-DRIVE Mobile SSD but it’s expensive and only allows a maximum of 2TB storage space.

There are also high end drives such as the OWC ThunderBay which supports the slightly slower Thunderbolt 2 (20 Gbps) and the WD My Book Thunderbolt Duo which supports the even slower Thunderbolt 1 (10 Gbps).

However, it is USB 3.0 (5 Gbps) that currently dominates the external hard drive market which has superseded the USB 2.0 (480 Mbps) ports that almost everyone has used at some point.

Confusingly, USB 3.0 has now been renamed USB 3.1 Gen 1.

All Macs from 2012 have at least one USB 3.0/USB 3.1 Gen 1 port and two Thunderbolt 1 or 2 ports although the good news is that most external drives with USB 3.0 are also backward compatible with USB 2.0 ports found on all older Macs.

macbook pro ports

To complicate things however, USB 3.1 Gen 2 (10 Gbps) is also now available which is even faster but faces the same problem as Thunderbolt – there are still very few manufacturers that support USB 3.1.

Firewire meanwhile has pretty much been abandoned by most external hard drive manufacturers although there are a few that still support it.

imac mac mini connection ports

As you can see, it seems that port connection standards, usually driven by Intel and Apple, are changing faster than external hard drive manufacturers can keep up with but to clarify things, here we’ll take a closer look at the sometimes bewildering world of external hard drive port connections on Mac.

USB 2.0 & USB 3.0

Almost all external hard drives for Mac now use a USB 3.0 port. If your Mac is from 2012 onwards then it will have at least one USB 3.0 port. You can check this by doing the following:

  1. Go to the Apple logo in the top left of your Mac and select “About this Mac”
  2. Click on “System Report” on the Overview tab
  3. Select USB down the left hand margin

usb 3.0

There you will see if you have a USB 3.0 port. Macs before 2012 only have USB 2.0 but the good news is that all USB 3.0 external hard drives are backwards compatible with USB 2.0 ports.

The only difference is you will get a maximum data transfer speed of 480Mbps compared to 5 Gbps with USB 3.0 (see the port connection speed comparison table below for an overview of speed differences between connection ports).

USB 3.1

USB 3.1 was released a few years ago and offers more than double the speed of USB 3.0 at 10Gbps (roughly the same as Thunderbolt 1). The problem is that most external hard drive manufacturers simply do not support it.

There are some models such as the Samsung T5 Portable SSD which is both an SSD drive and 3.1 compatible but only goes up to 2TB and is quite expensive.

Our advice is, don’t look for a USB 3.1 drive at this stage – the adoption by manufacturers and economies of scale simply still aren’t there.

Thunderbolt 1, 2 & 3 / USB-C

Since 2012, new Macs have Thunderbolt connections. Thunderbolt replaces the older Firewire connections and is now standard in all new Macs.

The latest MacBook Pros from late 2016 onwards have Thunderbolt 3 connections which offers speeds of up to 40 Gbps per second.

This is incredibly fast and easily allows you to edit video from your Mac as if it were on your Mac’s internal hard drive or even connect a 4K external monitor to.

Thunderbolt has been developed by Intel and Apple but uses the same connection port and cable type as USB-C which was developed separately by the USB Implementers Forum.

USB-C will eventually replace USB 3.1 although USB-C devices can only handle a top speed of 10 Gbps.

If you’ve got a pre-2016 Mac with a Thunderbolt 2 port, you’ll need a conversion cable from Apple to connect it to Thunderbolt 3 or USB-C ports.

If you’re backing up large amounts of data, a Thunderbolt compatible external hard drive is definitely worth the investment because it makes backups much quicker.

Or if you’re planning on regularly transferring or backing-up 4K video, a Thunderbolt connection makes creating backups and editing in real-time from an external hard drive much quicker.

However, there’s one big problem with Thunderbolt 3 and USB-C.

At the moment, there are still no external drives that actually support Thunderbolt 3.

The closest we’ve found is the OWC ThunderBay which supports Thunderbolt 2 capable of speeds of up to 20Gbps.

Beware that there are some manufacturers that claim to be “Thunderbolt 3” compatible but this is misleading as it merely means it can plug into a Thunderbolt 3 port – it does not deliver Thunderbolt 3 transfer speeds.

Always check the small print what the maximum transfer speed is – if it’s not at least 40 Gbps then it’s not Thunderbolt 3 compatible.

For this reason, at the moment in 2019, we advise against making Thunderbolt a priority when choosing an external hard drive for your Mac for several reasons which can be summarized as:

  1. External hard drives still haven’t caught up with the speed of Thunderbolt connections. A Thunderbolt port can transfer at a staggering 40Gbps but even the fastest hard drives can’t get anywhere near this.
  2. There are three types of Thunderbolt – version 1, 2 and 3 each faster than the last. The problem is that those Thunderbolt drives that do exist still use Thunderbolt 1 or 2 which is the slowest standard so you’re not even getting the best that Thunderbolt on the latest generation of Macs can offer.
  3. Those Thunderbolt drives that currently exist are mainly only Thunderbolt 1 compatible (10Gbps) and expensive for very little capacity compared with USB 3.0 drives which transfer at a very respectable 5Gbps. For example, LaCie offer a 4GB Thunderbolt 1 external hard drive but we would never recommend LaCie drives anyway to Mac users. If you must have a Thunderbolt drive, the best thunderbolt external drive for Mac is the WD My Book Thunderbolt Duo or if you want something really big, the OWC ThunderBay.


Macs before 2012 also have Firewire (400 and 800) ports but this standard is gradually being phased out and we don’t recommend getting a Firewire external hard drive.

The majority of manufacturers that still produce Firewire drives are not established brands either and therefore reliability may also be an issue.

However, if a Firewire port is important for you, we can recommend the well-respected and reliable OWC range of Firewire drives for Mac which support both Firewire and USB 3.0. OWC have been in the business over 25 years.

Apple has replaced Firewire ports on all Macs made after 2012 with Thunderbolt ports.

Note that if the external hard drive has a Firewire connection but you only have a Thunderbolt connection port on your Mac, you can use a Firewire to Thunderbolt adapter cable to connect it to your Mac although transfer speeds will be at Firewire speed, not Thunderbolt speed.

how to choose external hard drive - firewire port mac

The conclusion from all this is that in 2019, the fastest, most widely used and economical external hard drive connection that Mac users should focus on is USB 3.0.

All of the best external drives for Mac featured here use at least a USB 3.0 connection but we’ve also featured a few which support Thunderbolt as well.

To summarize the speed difference between the different connections check the comparison table below which is done in order of speed.

Speeds are measured in Megabits per second (Mbps) and faster devices such as USB 3.0 and Thunderbolt in Gigabits per second (Gbps).

Note that these are maximum speeds and real world speeds may be 10-20% less depending on the type of data being transferred and other factors.

As mentioned earlier, there are no external drives that can achieve these speeds yet and the best you can expect is around 100-200 Mbps transfer speed from most mechanical drives and about double that from an SSD drive.

Connection TypeSpeed
Firewire 400400 Mbps
USB 2.0480 Mbps
Firewire 800800 Mbps
USB 3.05 Gbps
USB 3.110 Gbps
USB-C10 Gbps
Thunderbolt 110 Gbps
Thunderbolt 220 Gbps
Thunderbolt 340 Gbps

The world of connection ports is changing rapidly and there’s an ongoing debate over which will eventually win out between USB 3.1 and Thunderbolt / USB-C.

At the moment though, it’s USB 3.0 that’s out in front.

For more on using USB 3.0 on Mac, check out Apple’s USB 3.0 FAQ.

12. Apple Airport Time Capsule

Apple offers its own tailor-made external hard drive, the Apple Airport Time Capsule.

Time Capsule works over your WiFi connection so the smart thing is, backups are performed wirelessly.

However, backing up via WiFi is also much slower than using an external hard drive connected with either a USB 3.0 cable or Thunderbolt connection.

apple airport time capsule

Apple’s Time Capsule is also considerably more expensive than most other external hard drives with similar capacity so unless wireless backups are important to you, there are better options available.

13. Format Types

You can format an external hard drive so that it works on both Mac and PC or Mac only.

The best models are ready formatted for use on Mac.

However, you can easily format any external hard drive on your Mac to work with both Mac and PC or Mac only. If you want to use the drive with both a Mac and PC it must be formatted in exFat or FAT32 format.

The problem is that FAT32 is limited to 4GB so for drives of 1TB or more, you have to use exFat.

If the drive you buy isn’t formatted for Mac and Time Machine you can find easy to follow instructions here.

14. Mac Backup Software

This could be an article in itself but we have absolutely no problem using Apple’s Time Machine software for backing up Macs and strongly recommend using it.

Time Machine is free in macOS, it’s quick and it’s easy to use. If anything happens to your hard drive, everything on your Mac including setup and configuration is saved in Time Machine.

Just plug Time Machine in case of data loss, operating system problems or plug it into a new Mac if your hard drive failed, and you can instantly roll back to the last working version of your Mac with all your files and folder.

There are other more manual solutions however, the best being CarbonCopy Cloner or SuperDuper for Mac.

Most external hard drive manufacturers also include their own backup and management software but they can be un-intuitive, inflexible and you really don’t need them.

Seagate’s Dashboard software for example is quite bloated and doesn’t make it easy to customize backups.

We hope you’ve found this guide to buying an external hard drive on Mac useful but if you have any questions, let us know in the comments below.

You can check out our selection of the best external hard drives for Mac here.

About The Author


MacHow2 is devoted to helping you get the most of of your Mac. We're passionate about all things Mac whether it's helping users with software recommendations or solving technical problems. If you've got any comments about this article, get involved by leaving a comment below. You can also contact us directly using the contact form at the top of the site. Please note that in the interests of transparency, MacHow2 may sometimes receive compensation from link clicks or vendors.

3 Responses

  1. MacHow2

    Nice article!

    A few bits of info to clarify info about ports:
    – USB 3.0 (5Gbps) has been renamed USB 3.1 Gen 1 and USB 3.1 (10Gbps) has been renamed USB 3.1 Gen 2, which can get confusing. To make matters worse, some products use the old naming and some use the new.
    – Thunderbolt 3 ports on Macs use a USB-C connector and these support USB 3 (.0 and .1) so you can plug in a USB 3.x device. Some USB 3 products may use a different connecter so may need a simple adapter to convert the connector to USB-C.

    Also a correction is needed: USB-C is only a connection type and is not tied to a specific speed (though it is commonly used with connection speeds of at least 10Gbps). So that part of the table should be removed.

    Also note that an Apple Time Capsule is typically (always?) connected to a network hub so can be accessed via an ethernet port, which increases access time significantly.

  2. MacHow2

    Just to edit my reply,
    “Some USB 3 products may use a different connector (typically USB-A) so may need a simple adapter to convert the connecter to USB-C.”

  3. MacHow2

    Maybe the table of Connection Types should be re-labeled “Connection Protocols” or “Standards” or something?


Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Subscribe to MacHow2!

Get notified when new articles are published and for special offers on Mac software.


By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.