How do I choose the best external hard drive?

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Answered by: Jack, An Expert in the Buyer's Guides Category
External Hard Drive Buyer’s Guide

Your photos, videos and documents are valuable, but they are also vulnerable. A spilled drink or a computer virus can destroy years of precious memories. An external hard drive is a great tool for backing up your important data, but finding the best external hard drive can be confusing. This guide will help you understand your options and find the product that suits your needs.

Storage Space

The capacity of a hard drive is rated in gigabytes or terabytes. A terabyte equals 1,000 gigabytes. A gigabyte is roughly equal to 30 minutes of video, 100 songs, 250 photos or 500 documents. A one terabyte drive is usually sufficient for most people, but you may need a larger drive if you have a lot of video files or a large iTunes library. Gamers may also need a larger drive, because computer games often take up tens of gigabytes.


Faster external hard drives will allow for quicker backups and file transfers. Most drives use the USB 2.0 protocol, which is capable of transfer rates up to 480Mbps. Some newer drives support USB 3.0, which is up to ten times faster.

Both types of USB are fully compatible with each other, but you’ll only get higher transfer speeds if your computer has USB 3.0 ports. You can check by looking at the USB ports on your computer - if they are blue, then you can use the faster USB 3.0 drives. Grey or yellow USB ports only support the slower USB 2.0 standard.

Mac users also have the option of using Thunderbolt hard drives. Thunderbolt is extremely fast with transfer rates of up to 40Gbps, but these drives are considerably more expensive. Most hard drives cannot take advantage of the greater speeds provided by Thunderbolt, so it is usually only a worthwhile feature on the Solid State Drives or RAID arrays used by professional photographers and video editors.

Form Factor

There are two main types of external hard drive, 2.5” and 3.5”. 2.5” drives are slightly larger than a smartphone and weigh about half a pound. 3.5” drives are about the size of a hardcover book and weigh about two pounds. The choice is a trade-off between portability and cost.

3.5” drives are cheaper per gigabyte of storage, but their size and weight means that they are best used with a desktop computer. 2.5” drives are more expensive and have less storage space, but they easily fit into a laptop bag and do not require an external power adapter. The best external hard drive is one that you use regularly, so it may be worth paying a premium for portability and convenience.


Windows and Mac OS include backup tools. Mac OS uses the very sophisticated Time Machine backup system, but the Windows backup tool is quite basic. If you have a lot of files, it’s worth looking for a drive that includes backup software.

Some hard drive manufacturers include encryption software, which protects your data if your external hard drive is lost or stolen. A cloud storage service is sometimes included, which allows you to access your data from anywhere via the internet.


A backup is useless if the external hard drive fails. Look for a drive with a three or five year warranty, as a longer warranty is usually a sign of high reliability. Portable drives are at risk of accidental damage, so build quality is an important factor. The cheapest external hard drives tend to have a fragile plastic chassis, but more expensive drives are usually encased in metal.

If you frequently travel with your external hard drive, you might need something particularly tough. Some manufacturers offer specially ruggedized drives with shock-proof rubber bumpers. External SSDs provide the ultimate in ruggedness, but are substantially more expensive than conventional hard drives.

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