The largest possible file for a FAT32 drive is 4GB minus 2 bytes. Win32-based applications can open files this large without special handling. However, non-Win32 applications must use Int 21h Function 6Ch (FAT32) with the EXTENDED_SIZE flag.
The FAT32 file system includes four bytes per cluster within the file allocation table. This differs from the FAT16 file system, which contains 2 bytes per cluster, and the FAT12 file system, which contains 1.5 bytes per cluster within the file allocation table.
Note that the high 4 bits of the 32-bit values in the FAT32 file allocation table are reserved and are not part of the cluster number. Applications that directly read a FAT32 file allocation table must mask off these bits and preserve them when writing new values.
File System Cluster Limits:
| System | Cluster Limit |
|---|---|
| FAT12 | The count of data clusters is less than 4087 clusters. |
| FAT16 | The count of data clusters is between 4087 and 65526 clusters, inclusive. |
| FAT32 | The count of data clusters is between 65526 and 268,435456 clusters, inclusive. |