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Definition of FAT32 in Network Encyclopedia.

What is FAT32?

FAT32 is an enhanced version of file allocation table (FAT), supported by Microsoft Windows 95 OSR2, Windows 98, and Windows 2000. FAT32 theoretically supports drives of up to 2 terabytes (2048 GB) in size, although for Windows 2000 the actual size limit is 32 GB. If the installation partition is smaller than 2 GB, it will automatically be formatted using FAT. If the installation partition size is equal to or greater than 2 GB, it will automatically be formatted as FAT32.

FAT32 uses a smaller cluster size than FAT so is more efficient at utilizing disk space on large volumes (those greater than 512 MB in size) than FAT. The savings in disk space using FAT32 instead of FAT for large volumes is typically 20 to 30 percent. The following two tables show the difference in cluster sizes between the original FAT and FAT32.

FAT Cluster Sizes

Drive SizeFAT Cluster Size
0 MB–32 MB512 bytes
33 MB–64 MB1 KB
65 MB–128 MB2 KB
129 MB–256 MB4 KB
257 MB–512 MB8 KB
513 MB–1024 MB16 KB
1025 MB–2048 MB32 KB

FAT32 Cluster Sizes

Drive SizeFAT32 Cluster Size
260 MB–8 GB4 KB
9 GB–16 GB8 KB
17 GB–32 GB16 KB
More than 32 GB32 KB

FAT32 in Windows 2000 and above

Using FAT32 (or FAT) with the Windows 2000 operating system platform is not recommended because it does not offer the security features that are provided by the NTFS file system. FAT32 also does not support disk compression. The only time you would use FAT32 with Windows 2000 is in a dual-boot situation, which Microsoft does not recommend.

Note that in a dual-boot system, FAT32 volumes cannot be accessed by any operating systems other than Windows 95 OSR2, Windows 98, or Windows 2000. For dual-boot with Windows 95, Windows 98, or Windows NT, drive C must be a FAT partition.