Portable hard drives are useful. Based on the 2.5-inch drive form factor, a portable hard disk is small, light and powered by the data transfer bus, so no additional power supply is needed. They're the ideal solution for carrying around large amounts of data.
Today's portable hard drives cram ever greater capacities into smaller and smaller enclosures. The seven drives we have on test here are all known for their slimline design. Despite capacities of up to 1TB, they're convenient enough to carry around in your pocket.
But it's not all about small form factor. We look at speed, connectivity and good old value for money.
1. Buffalo MiniStation 500GB - £62
This slick white drive is handy and pocket-sized. Out of the box it's FAT32- formatted, so it can't handle files of over 4GB, but it's easy enough to reformat it for Mac OS in Disk Utility.
The drive is 14mm thick, and its USB 3.0 connectivity is backwards-compatible with the USB 2.0 format used by all Macs. Its read speeds were just below average, but write speeds were good. Its cost per GB of 12.4p (based on its current Amazon price) is good value for money.
A solid, workmanlike performer. Attractive, well built and very portable.
2. Freecom Mobile Mg 750GB - £116
This German pocket-sized portable hard drive is built to last, with its large capacity and strong, lightweight magnesium enclosure.
Preformatted for Mac OS, it's the only drive we tested that offers FireWire 800 connectivity as well as USB. It's USB speeds were about average, though we'd have expected more from its FireWire 800 scores. It comes with a couple of trivial apps, but no FireWire 400-to-800 cable for older Macs.
Excellent minimalist design and very good build quality make this a good choice.
3. G-Drive Slim 320GB - £63
You can tell at a glance the G-Drive Slim is built with Macs in mind. Its brushed aluminium finish is the perfect match for a MacBook Pro. It's Mac-formatted out of the box too, though there's no FireWire connectivity – it's USB 2.0-only.
At only 10mm thick and with a total volume of just under 105cm3, it's one of the smallest drives we tested, though at 19.7p per GB its capacity works out a little expensive, even allowing for the fact that lower capacity drives are at a disadvantage here.
Gorgeous, Mac-like and compact enough to carry around in your pocket.
4. Seagate GoFlex Slim 320GB - £74
Although the most expensive drive on a cost-per-GB basis, at 9mm thin and just under 86cm3, it's also the smallest. Its USB 3.0 port is housed on a removable cap that can be replaced with a FireWire 800 connector; a Thunderbolt version is coming soon too.
Seagate's GoFlex Slim is NTFS formatted, but comes supplied with a driver so your Mac can write to as well as read from NTFS drives, making it ideal for swapping large files with PCs.
The slimmest drive on offer here. It comes supplied with some useful software too.
5. Iomega Prestige 500GB £50
This black metal drive looks gorgeous, and is the only drive tested here to come supplied with a double-headed cable to draw power from two USB ports where necessary.
It's NTFS-formatted out of the box, a format Macs can read from, but not write to. Unless you have a driver such as Paragon's NTFS for Mac installed, you'll have to reformat it using Disk Utility.
Build quality is very good too. It's not the most compact drive on test, but it's certainly robust.
A good-looking, well-built and versatile drive with prestige to match its name.
6. LaCie Rikiki Go 1TB £77
LaCie's Rikiki Go features an integrated USB cable, but it's far too short for anything other than laptop use. Good job you can remove it and use a standard USB cable if you wish, though there isn't one in the box.
At 19mm thick and just under 157cm3 it's the bulkiest drive on test, but not by a great deal. This is partly due to its 1TB of storage, which is also the largest one tested here.
It's NTFS out of the box, so you need to reformat it before use, unless you have an NTFS driver installed on your Mac.
It sports the biggest capacity, but it's the bulkiest drive here. Useful in-built USB cable.