Solid-state storage may be sexy, but if you’re looking for huge capacity and tiny prices, then the classic hard disk remains unbeaten. Available capacities of portable drives with laptop-style disks inside now extends up to a whopping 4000GB, more commonly referred to as 4 terabytes (TB).

Most portable USB drives are powered by the connected computer, so you can use them on the move without the need to plug into the mains or use batteries. Some will even connect your phone or tablet and let you extend storage that way, or allow you to transfer or open files.

Also see: Best Tech Deals

Capacity

Even in the smallest portable drives you’ll likely find are 128GB in size, which is enough to space thousands of CD albums in lossless FLAC format, or even more in lower quality MP3 or AAC formats. Off-loading your music collection alone from a computer to a portable drive can be a godsend in freeing valuable space if your laptop has limited storage.

Another popular application of portable storage is for keeping critical backups of your data held on a PC or laptop. You may be able to keep a perfect clone of your entire computer’s internal drive, on standby and ready in the event that the computer is lost or its drive should malfunction.

Alternatively, you may choose just to back up the most important files and documents from your user libraries, such as text documents, photos, films, music and stored email. Some portable drives include software that can help automate this process, keeping your selected directories in sync whenever you plug in the drive or by a daily schedule.

Performance

Now that USB 2.0 has been banished from all self-respecting storage, we find USB 3 as the standard for connection, letting these portable drives perform as quickly as the little disks inside will allow.

This means that when transferring your music or video collection to or from your PC, you can expect around 100MB/s read speed (and typically the same for writing, since unlike flash storage technology the read and write speeds tend to be more symmetrical).

Compare this with the older drives using USB 2.0, which would limit speeds to around 35MB/s, or only one-third the speed. So in real terms, your 100GB of media files would take close to an hour to transfer with USB 2.0, or under 20 minutes using USB 3.0.

If you’re likely to be storing or backing up many small files, be aware that overall performance will plummet since hard disks tend to choke on smaller files. So while large files may zip across at 100MB/s, the smallest will likely travel at less than 1MB/s, or one hundredth that speed.

USB 3 is confusing, as USB 3.0 was retrospectively renamed to USB 3.1 Gen 1. There’s also a new version, USB 3.1 Gen 2. This doubles the potential throughput from Gen 1’s 5Gb/s to 10Gb/s. In megabytes per second, these equate to 625 and 1250 respectively. Pretty fast, then.

In reality, the fastest SSDs top out at around 550MB/s and this speed is highly dependent on the device you’re connecting it to.

Protection

A rugged exterior will be handy if you want the freedom of being able to throw around the unplugged drive with less worry that it will damage the unit; and more importantly lose your data.

Look out for shock-resistance ratings such as the US military MIL-STD-810F 516.5 (Transit Drop Test). This means that it should withstand being dropped 26 times onto a hard floor, once on to each face, edge and corner, from a height of 1.22m.

Flash storage - more commonly known as SSDs - can survive more brutal treatment, and some portable drives are even water resistant. If you were to accidentally drop a portable SSD drive in water, then as long as the port covers are firmly closed, it will work fine to use it after it has been fully dried.

Reliability

It’s tough to say definitively which manufacturer makes the most reliable hard drives. While there’s a big difference between the technology used in traditional hard drives and SSDs, both have a limited lifespan, and this is why warranties are relatively short - typically two or three years.

What’s important is that you have a well-thought-out backup process and you don’t rely on any single drive to store precious files. Ideally you should have three copies: one on a PC or phone / tablet, one on a backup drive and one in the cloud.

Value

For many users, a portable storage drive may be an unavoidable commodity, and price will be the deciding factor. We give a value rating based on how much each gigabyte of storage is costing you for each drive. Particularly with a 3TB drive, you can expect to find storage for under 4p per gigabyte now.

Security

The larger the drive, the more you can store - and the more you stand to lose in the event of losing the drive or having it stolen. This is where it pays to lock down that drive.

There are two ways to ensure the data is unreadable by other users. You can scramble the contents through hardware encryption. Or you can use a software application to encrypt either parts or all of the drive.

Best portable hard drive reviews

1. Adata SE730

Adata SE730
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 31 August 2016

Typically if you want a tiny, high-capacity drive you have to sacrifice performance, but not with the SE730. It really is a pocket rocket, and well worth the price if you need speedy portable storage.

Read our Adata SE730 review.

2. Samsung Portable SSD T3

Samsung Portable SSD T3
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 31 August 2016

If you’re after a large capacity portable drive for backing up your photos, videos, music and other precious data, the Samsung T3 is a great choice. However, a traditional hard drive is still much, much cheaper if speed isn’t your main priority.

Read our Samsung Portable SSD T3 review.

3. Transcend ESD400K

Transcend ESD400K
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 20 September 2016

The Transcend ESD400K is a very light, portable and blisteringly fast portable SSD drive. At only 56g, the portable drive is easy to carry around and competes with some of the very best portable drives in the market.

Read our Transcend ESD400K review.

4. SanDisk Extreme 500 Portable SSD

SanDisk Extreme 500 Portable SSD
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 31 August 2016

For those that need high-speed portable storage, the Extreme 500 is a solid choice. Capacities extend to 480GB which should be fine for most people. If you need more, look no further than the Samsung T3.

Read our SanDisk Extreme 500 Portable SSD review.

5. WD My Passport 4TB

WD My Passport 4TB
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 11 October 2016

As a high-capacity portable drive, the WD My Passport 4TB (2016) offers cloud services, hardware encryption and has respectable performance for a HDD.

Read our WD My Passport 4TB review.

6. Toshiba Canvio Connect II

Toshiba Canvio Connect II
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 31 August 2016

Aside from speed, the Toshiba Canvio Connect II is a brilliant all-round package. It offers acres of space for your backups and media library, it’s cheap and it comes bundled with genuinely useful software.

Read our Toshiba Canvio Connect II review.

7. Seagate Backup Plus Ultra Slim 2TB

Seagate Backup Plus Ultra Slim 2TB
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 21 September 2016

The Seagate Backup Plus Ultra Slim is not a top performer, but with its 2TB storage and super slim design, the Seagate portable drive is fantastic for backing up documents.

Read our Seagate Backup Plus Ultra Slim 2TB review.

8. Freecom mHDD Slim 1TB

Freecom mHDD Slim 1TB
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 23 September 2016

Despite having an expensive price per GB, the Freecom mHDD Slim 1TB is a stylish, well-made portable hard drive.

Read our Freecom mHDD Slim 1TB review.

9. Freecom Tablet Mini SSD

Freecom Tablet Mini SSD
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 31 August 2016

If you’re specifically after a portable drive which can connect to your phone or tablet to provide extra storage or act as a backup for its photos and videos, the Freecom is a decent choice. It isn’t stylish nor is it the cheapest, but it performs well and is convenient thanks to the built in USB cables.

Read our Freecom Tablet Mini SSD review.

10. Seagate Backup Plus Slim 2TB

Seagate Backup Plus Slim 2TB
  • Rating: ratingsratingsratingsratingsratings
  • Reviewed on: 19 August 2015

The Seagate Backup Plus Slim is a well-rounded portable hard drive which offers good value for money, design and speed. PC and Mac compatibility out-of-the-box is a decent feature and the Seagate Dashboard software is easy to use offering PC, mobile and social backup. There's very little to dislike here.

Read our Seagate Backup Plus Slim 2TB review.