Your Buying Guide To The Best USB External Hard Drive (HDD)

If you’re like many people, you’ve been slowly but surely accumulating media on your computer. Maybe you have 4,000 digital photos sitting in folders on your desktop, or maybe you’re a hardcore music collector who has been downloading from iTunes like a fiend. Either way, that media takes up precious space on your computer and needs to be stored properly—external hard drives can take care of that. It’s always a good idea to back up your computer. You may not trust your content to be stored in the cloud, so if you want a physical copy of your computer’s files – not just something that’s floating in the ether – you’ll want to buy an external hard drive (HDD). External hard drives promise almost unlimited storage: For less than $100, you can add a terabyte of data to your PC or Mac, laptop or desktop. That’s enough for over 750,000 MP3s or photos, or over 230 full-length movie files.

Every computer out there, from mega-huge towers to budget-priced Windows tablets, can connect to at least one hard drive. If you’re lucky enough to have multiple input/output ports, you can hook up many more. Auxiliary storage allows you to back up your system files, in case your primary system goes kaput.

Why You Need One

Leaving your content on your computer without backing it up is a no-no for several important reasons. For one thing, it slows down your computer. And for another — and this is crucial — you run the risk of losing everything in the event of a hard-drive crash. Don’t say it won’t happen to you because I bet you know at least one victim to this scenario. I know I do. Even a relatively small external drive will be able to tide you over for quite some time if you’re just a small-time media collector.

The disadvantage of cloud storage
One solution might be to rent storage space in the cloud, but buying a hard-drive’s worth of capacity is prohibitively expensive: 500GB of storage on Dropbox, for example, will set you back $499 per year. If you need just storage, as opposed to a service for file syncing or collaborating via the cloud, buying a portable hard drive is far more economical. For less than $200, you can get a 2TB drive that supplies four times the capacity of a Dropbox account. Pay for that storage capacity once, and you’ll own it forever—and you can take it with you wherever you go. Before you can choose the right drive, however, you have to identify your needs, wants, and budget.

Specify Your Needs
When deciding what’ll work best for your needs, consider the following: What will you be using it for; how much space do you really need; and how often will you be backing up your files? Also, do you want to be able to transport your external hard drive so that a lighter, encrypted one would be most convenient and best protected; or do you plan to keep it in one place, in which case you can afford a heavier but potentially cheaper device?

Answering these questions will help you gauge what the best storage device option will be for you right now.

External Hard Drive Types

External hard drives exist in many forms to accommodate a wide range of uses. They are for both desktop and mobile use, with hard disc drive or solid state technology, large size format, or a slimline profile that sits upright. But generally there are two types of external drives. Desktop-style drives, with 3.5-inch mechanisms inside, intended to stay put on a desk and require external power from a dedicated AC adapter. If you have any data you care about—important documents, photos, videos, or anything else—you need to have them backed up, or you will lose them eventually. Desktop hard drives are a great onsite backup option and a must-have in case your computer’s primary drive bites the dust. If you’re buying a desktop-style drive for active use (video or lots of file transfers), look for one with a built-in fan, as the extra cooling will extend the drive’s life expectancy.

Notebook-class (a.k.a. pocket) hard drives are usually 2.5-inch mechanisms powered through the connector cable . A 2.5-inch model can fit in a coat pocket and some pants pockets.

Desktop-style drives currently top out at 6 terabytes (TB) per mechanism, but some drive manufacturers put two to four mechanisms into a drive chassis for more storage (i.e., two 4TB drives equal 8TB of storage). Notebook-class drives come in capacities up to 2TB, but capacities from 500GB to 1TB are more common.

A word about multiple drives: You can increase capacity, speed or data protection by buying an external RAID array, but multiple drives add expense and (some) complexity. Once you connect a simple (single volume) external RAID array to your PC or Mac, it will show up and act as any other external drive. After that, it can become more complex. You should consider a drive with support for RAID levels 1, 5, or 10 if you’re storing really important data that you can’t afford to lose. There are other RAID levels for speed, capacity, and other factors like software vs. hardware RAID.

External solid-state drives (SSDs) were found mostly in the notebook-class form factor, and now they mostly come in mSATA form factor, but these are still relatively rare because they’re pricey in terms of cost per gigabyte. They’re currently limited to smaller capacities, specifically in the 128GB to 1TB range. [You may check our best external SSD picks for more information on the prices] We recommend that you buy SSDs for use as internal rather than external drives. Besides, unless you’re looking for SSD’s shock-resistance attributes, the drive will be wasted if you use the USB 2.0 interface (rather than, say, Thunderbolt or USB 3.0/3.1) to connect the SSD to your system, since the transfer rate of USB 2.0 is so much slower than either these three interfaces. Thunderbolt, and USB 3.0 external SSD drives are available now, but they are much more expensive than spinning hard drives: for example, a simple 1TB USB 3.0 (spinning) hard drive goes for about $65 to $75, while a 1TB SSD using USB 3.0 costs from $350 to $450. [Check our list of the best & fastest external portable hard drives.]

Input, Need Input

External storage devices are basically one or more internal drives put together inside an enclosure and connected to a computer using a peripheral connection.

There are four main peripheral connection types: USB, Thunderbolt, FireWire, and eSATA. Most, if not all, new external drives now use just USB 3.0 or Thunderbolt or both. There are good reasons why.

USB 3.0 offers a cap speed of 5Gbps and has the benefit of being backwards-compatible with USB 2.0 (it will connect to USB 2.0 ports, but will transfer but at the slower USB 2.0 speeds). Thunderbolt caps at 10Gbps (or 20Gbps with Thunderbolt 2.0), and you can daisy-chain up to six Thunderbolt drives together without degrading the bandwidth. Thunderbolt also makes RAID possible when you connect multiple single-volume drives of the same capacity. Note that more computers support USB 3.0 than Thunderbolt, especially among Windows computers. All existing computers support USB 2.0, which also works with USB 3.0 drives (though at USB 2.0 data speeds).

Some very new external hard drive may include more esoteric connectors like USB 3.1/USB-C or iSCSI. USB 3.1/USB-C and iSCSI are still very rare on drives. iSCSI is mainly used on professional-grade drives like the DroboPro. USB 3.1 is a newer standard, supported using the smaller USB-C connector. It has the same theoretical speed as original Thunderbolt (10Gbps), but is governed by the same group of companies that developed the other formats of USB. USB 3.1/USB-C uses smaller plugs and jacks compared with traditional USB, but it can use compatible hardware: a handful of USB memory sticks and hard drives are currently available with both USB 3.0 and USB 3.1 support via two separate connectors. Optional adapters will let you use older USB drives with PCs with newer USB-C ports.

Generally, speed is not the most important factor for non-Thunderbolt external drives that incorporate USB 3.0. That may seem counterintuitive, but the reason is that the USB 3.0 connectivity standard, which is the fastest among all non-Thunderbolt standards, is slower than the speed of SATA 3 internal drives.

Is Drive Speed Important?

Some drive manufacturers will crow about the speed of their drive mechanisms. While a 7,200rpm drive is inherently faster than a 5,400rpm drive, the true answer would be “it depends.”

The rate at which a hard drive spins its platters has a direct effect on how fast it can read and write data. A drive spinning at 7200 rpm will deliver much better performance than a drive spinning at 5400 rpm. Therefore if you plan to back up your computer every other week or so, most external hard drives will suffice. If you’ll mostly be using it to store large files, such as videos, however, you may prefer a device that takes in data from your computer more quickly. In this case, a hard drive with a USB 3.0 interface, as opposed to one with a USB 2.0 interface, would be best. That’s because the other aspect to hard drive speed is how quickly it can transfer data. This relates to its connectivity options, not the disc itself. A customer needs to choose an external hard drive with an interface that is compatible with their computer’s interface.

Moreover, If you are transferring lots of files over a speedy interface like USB 3.0/3.1 (fast), or Thunderbolt (fastest), then by all means go for the 7,200rpm drive. However, if you’re limited to USB 2.0 or FireWire 400/800, then I would trade speed for capacity and get the largest 5,400rpm drive that your budget allows. USB 2.0 and FireWire 800 are older interfaces that work fine with a 5,400rpm drive. Although USB 2.0 is still common, the interface copies your files at a speed 10 times slower than its newer counterpart.

If all-out speed is your goal, multiple drives (7,200rpm, 10,000rpm, or SSD) over Thunderbolt 2 is the fastest (and most costly), with a single SSD connected via Thunderbolt or USB 3.0/3.1 as next fastest, and so on. [Check our best USB 3.0 external SSD list.]

The downside of the faster drives is that they are inclined to overheat more quickly. In some cases, this may necessitate more frequent rest periods.

Storage Capacity

Capacity is the amount of data that a storage device can handle. Generally, we measure the total capacity of a drive or a storage system in gigabytes. On average, 1GB can hold about 500 iPhone photos, or about 200 iTunes digital songs.

Currently, the highest-capacity 3.5-inch (desktop) internal hard drive can hold up to 8 terabytes, or 8,000GB. On laptops, the top hard drive has up to 2TB of space and an SSD can store up to 2TB (Samsung recently released its first 2TB SATA III SSD which is the largest consumer SSD available at the moment) before getting too expensive to be practical.

Storage capacity in external HDDs can range from about 2GB to 4TB. In fact, some drive companies put two 4TB drives in one chassis, creating an 8TB HDD, which is total overkill for most people. For reference, computers these days usually come with anywhere between about 250GB and 750GB of space in the hard drive. Whether you want a mini external HDD (also known as a flash drive) that you can pin to your keychain and store a few important documents on, or a considerably larger one where you can keep all of your photos, songs, and videos, the possibilities are almost endless. A smart size for people looking to store videos would be 1TB or 2TB. If you’re mostly just storing emails and word documents, a smaller one could do. The more files you want to store, and the larger the file type (photos and videos are larger than word documents), the bigger you should go. External hard drives with a decent amount of space can start at under $70 and go upwards of $3,200.


If you intend to keep your external hard drive at home, going for one that costs less but weighs more might make sense. If you plan to tow it back and forth from home to work, you may want to pay a little more for a pocket-sized device. If you plan to transport it often, another practical feature for your device is enhanced data protection, which will reduce the risk of failure caused by shock if you happen to drop it. A portable storage unit should also offer durability to protect your files from shock and damage. Avoid anything flimsy and look for drives featuring solid, durable materials like quality plastic or aluminum.

Desktop-style drives, although also technically portable, are designed to stay put and require a power adapter. If you’d rather have something thin and light that you can simply plug into your computer without an external power source, this isn’t the type of drive for you. Make sure to look for one with a built-in fan if you’re going to be using it frequently and for heavy file transfers. A built-in fan will help extend the life of the HDD.


The vast majority of portable hard drives are 2.5-inch mechanisms, but not all portable hard drives are the same size. Some models come housed in low-profile enclosures, while others are wrapped in shock-absorbing material within ruggedized cases. Such design decisions affect the drive’s overall weight, but they also influence how well the drive can survive misadventure. If you’re a frequent traveler who grudges every ounce that goes into your laptop bag, you’ll need to work out for yourself the right balance between data security and tolerable shoulder load.

Some manufacturers, including Seagate and Western Digital, offer accessory cases for their drives that can add shock protection. We especially like the Nomad hard-shell case for Western Digital’s Passport drives. The amply padded, 6.25-ounce polycarbonate case has an opening for a USB cable, so you don’t have to remove the drive to use it.

Also you can opt for a product that comes with layers of physical protection, such as the Silicon Power Rugged Portable External Hard Drive. These drives are generally great for people working in rough environments.

Security & Encryption

Some drives just act as storage boxes; they’ll hold your data and nothing more. Others provide some measure of extra security, whether it’s automatic backup or file retrieval. These features typically cost extra, so it’s up to you whether you want to spend the money for the peace of mind they’ll bring.

Make sure also that your external hard drive comes with hardware-based encryption, which is more dependable than software-based encryption. This is especially important if you want to purchase a portable mobile drive to carry around, but it’s also important if you’re storing highly sensitive information. Carrying your private files around makes them more prone to loss and theft, so go the extra step and make encryption a concern.


Do you have a PC or a Mac? Make sure to keep this in mind when shopping since some hard drives are only compatible with PCs or Macs – but not both. If you buy a PC-specific hard drive for a Mac, you’ll either have to reformat the hard drive you buy, or be limited to one that is PC- or Mac-specific.


If you’re a solo computer user, you can usually get away with a simple external hard drive. But if you’re a small-business owner or you have multiple computers in your house, you should look into getting a network-attached storage device, or a NAS. These are, simply speaking, external hard drives with very large capacities that can automatically back up several computers and allow various computers to access the same files.

They cost more than the bare-bones external hard drives—sometimes much more, depending on the size and how many computers you plan to back up—but they are invaluable devices if you’re running on multiple computers.

Ease of use and reliability

If you’re a newbie or not in the mood to fuss with installing and configuring utility software, choose a drive with included software. It’ll just make things that much easier. Still, nothing is fail-safe, so buying a warranty isn’t a bad idea, especially one that lasts for considerably longer than a year since you should be able to use an external hard drive for several.

Final Warning

Remember: It costs much less to back up your data now than it will to pay a company to try to retrieve it later. And paying a retrieval service is no guarantee that you’ll get back what you’ve lost.

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