What Are FAT, FAT32, and NTFS ?

FAT (or FAT16) dates back to DOS 3.0, and FAT32 was introduced with the OSR2 update to Windows 95. NTFS (NT file system) is a more mature version of FAT32 that was originally designed for use with Windows NT and Windows 2000 for server applications. Each partition on a hard disk and each removable disk must be formatted with FAT, FAT32, or NTFS, but it's possible (and often desirable) to have some disks with one format and some with the other format on the same system.

Here are some facts about each of the file systems:

FAT Partitions are limited to 4GB. Files are limited to 2GB. Works on floppy disks. Readable by DOS, OS/2, and all versions of Windows. Does not work with domains (server-based network security). Not recommended unless you need to share data with a DOS, OS/2, or Windows 95 system.

FAT32 Partitions can be from 512MB to 2 terabytes, although Windows XP can format a FAT32 only as large as 32GB. Files are limited to 4GB. Readable by Windows 95 OSR2, 98, Me, NT, 2000, and XP. Does not work with domains. Recommended for home systems with no security needs, and for systems that need to share data with a Windows 98 or Me system.

NTFS Partition size can be from 520MB to 2 terabytes (larger sizes are possible, but not recommended). Files are limited only to the size of the partition. Can't be used on floppy disks. Readable by Windows 2000 and XP, and by Windows NT 4.0 with Service Pack 4 or later. Required for domains. Enables encrypted folders and files, permissions for individual folders and files, and disk quotas by user. Windows XP uses NTFS 5.0 (it was called 5.1 during product testing), a very slight upgrade from the version used in Windows 2000. Recommended for systems with security needs, large hard disks, and LAN connections.

Both FAT32 and NTFS are designed for large partitions and disks and offer no significant benefits when used on smaller disks. However, with XP's rather significant system requirements it will be unlikely to see a system available with less than 10GB of hard drive space, making FAT16 largely useless.


NTFS 5.0 was introduced with Windows 2000. The original NTFS that was used by Windows NT does not have the same features as NTFS 5.0. Partitions made with Windows NT need to be converted for Windows XP to use them. Windows XP automatically converts Windows 2000 to the slightly updated version of NTFS that it uses. Older versions of some partitioning utilities (like PartitionMagic version 6) don't work with Windows XP' NTFS partitions: be sure to get the latest versions.


NTFS 5.0 offers all of the advantages of FAT32 as well as the following:
More efficient use of space NTFS can allocate as little as 2K of disk space to a file, reducing wasted disk space.
On-the-fly compression Individual files can be compressed and decompressed as needed. Entire drives can be reduced in size without affecting overall performance.
Encryption Files and folders can be encrypted with a user's password.


Source :

 "Windows XP The Complete Reference"
By John R. Levine, Margaret Levine Young, Rima Regas, Douglas Muder, and Alison Barrows