Tip #8: Is your hard disk FAT or NTFS?

The first thing that you should do as soon as you purchase a new external hard disk, is to check what filesystem it is formatted with.

The filesystem can be thought of as the "format" of a hard disk. There are several filesystems currently in popular use: FAT (FAT32 to be precise), NTFS and HFS+. Usually most external hard disks nowadays come pre-formatted as FAT, but some also come as NTFS, and if the packaging of the hard disk specifically mentions "for Mac", it should be in HFS+. It is important for you to recognise some of the characteristics of these filesystems to avoid the hassle of reformatting your hard drive later on.


FAT (File Allocation Table) is quite an old filesystem which was developed by Microsoft and used in Windows operating systems until Windows XP was introduced. FAT has gained commonplace in portable storage devices with smaller storage capacities, such as USB flash drives ("pendrives") and camera memory cards. The reason behind this is because FAT is relatively simple to manage, even for devices such as cameras and DVD players which have less computing power compared to a normal PC. Therefore, computers running any operating system are also capable of reading and writing to disks formatted to FAT. However, FAT is limited to saving files with a maximum size of 4GB. When FAT was created, the developers did not anticipate files to be as huge as or huger than 4GB in size.

After FAT comes NTFS (New Technology File System), yet another filesystem which was developed by Microsoft to supersede FAT. NTFS has astronomically higher file size limits (the biggest file you can save is 16 exabytes, 1 exabyte is about 1 billion gigabytes) and also other features like file compression and security. It is the main choice of filesystem for internal hard disks of computers running Windows XP, Vista and 7. If you are using a Windows computer bought within the last 5 years, it should be using NTFS already. It is worth noting that most consumer devices (cameras, DVD players, TVs) still do not support reading media formatted as NTFS, these should remain formatted as FAT. Additionally, note that Macs by default can only read and not write to NTFS disks without additional software.

HFS+ (Hierarchical File System Plus, also Mac OS Extended) is the current filesystem in use by all present day Macs. The file size limit here is 8 exabytes, half of that of NTFS (who would have a hard disk that big?). Like NTFS, HFS+ is not supported by most consumer devices. Windows computers are unable to read nor write to HFS+ disks unless special driver software is installed.

To sum things up in a table:

Filesystem	Max file size	Windows		Mac		Consumer devices
		Read	Write	Read	Write	Read	Write
FAT	4 GB	✔	✔	✔	✔	✔	✔
NTFS	16 EB	✔	✔	✔	✘	✘	✘
HFS+	8 EB	✘	✘	✔	✔	✘	✘

If you intend to use your new external hard disk mainly on Windows computers only, format it using NTFS so that you can take advantage of the huge capacity to save files such as DVD images or high-definition videos which are usually bigger than 4GB. Likewise, if you are using a Mac, and you intend to use it on Macs only, format it to HFS+.

What about pendrives? Since pendrives have relatively smaller capacities compared to hard disks, they should remain formatted to FAT, so to maintain compatibility with all computers and consumer devices. It won't hurt to occasionally format it to NTFS or HFS+ to accommodate a large file you may want to bring with you, but just to note, some space is wasted to maintain information about files on the drive, and this space wastage is more apparent in disks formatted as NTFS or HFS+ than those which are FAT. To illustrate this, I have formatted my 8GB pendrive to NTFS and FAT, and showed the Properties page of the disk in each case respectively.

NTFS	FAT

To format a hard disk in Windows:

1. Open My Computer.
2. Right click on the disk you want to format, choose Format.
3. Choose the filesystem (FAT32 or NTFS).
4. (optional) Type a name for the disk in Volume label.
5. (optional) If you want Windows to check for any damages on your disk, untick the Quick format option. Otherwise, leave it ticked.
6. Click Start.

Formatting a disk will erase all files on it, therefore if you are faced with a situation where you have to switch to another filesystem, you would have to move all your files to another hard disk, format it and move them back in again. End of the day, make sure you choose a filesystem for your new hard disk and format it appropriately, so to avoid the need to reformat it later on.