What is FAT32?

This article describes the FAT32 file system that is included with Windows 95 OEM Service Release 2 (OSR2), Windows 98, and Windows Millennium Edition (Me).

Windows 95 OSR2, Windows 98, and Windows Me include an updated version of the FAT file system. This updated version is called FAT32. The FAT32 file system allows for a default cluster size as small as 4 KB, and includes support for EIDE hard disk sizes larger than 2 gigabytes (GB).

NOTE: Microsoft Windows NT 4.0 does not support the FAT32 file system.

FAT 32 Features

FAT32 provides the following enhancements over previous implementations of the FAT file system:

  • FAT32 supports drives up to 2 terabytes in size.

    NOTE: Microsoft Windows 2000 only supports FAT32 partitions up to a size of 32 GB.

  • FAT32 uses space more efficiently.

    FAT32 uses smaller clusters (that is, 4-KB clusters for drives up to 8 GB in size), resulting in 10 to 15 percent more efficient use of disk space relative to large FAT or FAT16 drives.

  • FAT32 is more robust.

    FAT32 can relocate the root folder and use the backup copy of the file allocation table instead of the default copy. In addition, the boot record on FAT32 drives is expanded to include a backup copy of critical data structures. Therefore, FAT32 drives are less susceptible to a single point of failure than existing FAT16 drives.

    FAT32 is more flexible. The root folder on a FAT32 drive is an ordinary cluster chain, so it can be located anywhere on the drive. The previous limitations on the number of root folder entries no longer exist. In addition, file allocation table mirroring can be disabled, allowing a copy of the file allocation table other than the first one to be active. These features allow for dynamic resizing of FAT32 partitions.

  • Creating FAT32 Drives

    In Windows 95 OSR2, Windows 98, and Windows Me, if you run the Fdisk tool on a hard disk that is over 512 megabytes (MB) in size, Fdisk prompts you whether or not to enable large disk support. If you answer “Yes” (enabling large disk support), any partition you create that is larger than 512 MB is marked as a FAT32 partition.