FAT32

In order to overcome the volume size limit of FAT16, while still allowing DOS real mode code to handle the format without unnecessarily reducing the available conventional memory, Microsoft implemented a newer generation of FAT, known as FAT32, with cluster values held in a 32-bit field, of which 28 bits are used to hold the cluster number, for a maximum of approximately 268 million (228) clusters. This allows for drive sizes of up to 8 terabytes with 32KB clusters, but the boot sector uses a 32-bit field for the sector count, limiting volume size to 2 TB on a hard disk with 512 byte sectors.

On Windows 95/98, due to the version of Microsoft's SCANDISK utility included with these operating systems being a 16-bit application, the FAT structure is not allowed to grow beyond around 4.2 million (< 222) clusters, placing the volume limit at 127.53 gigabytes.[14] A limitation in original versions of Windows 98/98SE's Fdisk utility causes it to incorrectly report disk sizes over 64GB. A corrected version is available from Microsoft. These limitations do not apply to Windows 2000/XP except during Setup, in which there is a 32GB limit. Windows Me supports the FAT32 file system without any limits. However, similarly to Windows 95/98/98SE there is no native support for 48-bit LBA in Windows ME, meaning that the maximum disk size for ATA disks is 127.6GB, the maximum size of an ATA disk using the previous long-standard 28-bit LBA.

FAT32 was introduced with Windows 95 OSR2, although reformatting was needed to use it, and DriveSpace 3 (the version that came with Windows 95 OSR2 and Windows 98) never supported it. Windows 98 introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of data. In the NT line, native support for FAT32 arrived in Windows 2000. A free FAT32 driver for Windows NT 4.0 was available from Winternals, a company later acquired by Microsoft. Since the acquisition the driver is no longer officially available.

Windows 2000 and Windows XP can read and write to FAT32 file systems of any size, but the format program included in Windows 2000 and higher can only create FAT32 file systems of 32 GB or less. This limitation is by design and according to Microsoft was imposed because many tasks on a very large FAT32 file system become slow and inefficient. This limitation can be bypassed by using third-party formatting utilities or by using the built-in FORMAT.EXE command-line utility.

The maximum possible size for a file on a FAT32 volume is 4GB minus 1 "null" byte (232-1 bytes). Video applications, large databases, and some other software easily exceed this limit. Larger files require another formatting type such as HFS+ or NTFS. Until mid-2006, those who run dual boot systems or who move external data drives between computers with different operating systems had little choice but to stick with FAT32. Since then, full support for NTFS has become available in Linux and many other operating systems, by installing the FUSE library (on Linux) together with the NTFS-3G driver. Data exchange is also possible between Windows and Linux by using the Linux-native ext2 or ext3 file systems through the use of external drivers for Windows, such as ext2 IFS; however, Windows cannot boot from ext2 or ext3 partitions.