mkfs.fat

Create a FAT filesystem inside partition Y on device X

$ sudo mkfs.fat [/dev/sdXY]

$ sudo mkfs.fat -n [volume_name] [/dev/sdXY]

$ sudo mkfs.fat -i [volume_id] [/dev/sdXY]

$ sudo mkfs.fat -F [12|16|32] [/dev/sdXY]

$ sudo mkfs.fat -f 4 [/dev/sdXY]

$ sudo mkfs.fat -c [/dev/sdXY]

mkfs.fat [-a] [-A] [-c] [-C] [-f number-of-fats] [-F fat-size] [-i volume-id] [-l bad-block-file] [-n volume-name] [-r root-entries] [-R reserved-sectors] [-s sectors-per-cluster] [-S sector-size] [-v] device [block-count]

mkfs.fat creates MS-DOS FAT filesystems on devices or image files. It supports FAT12, FAT16, and FAT32 variants used by DOS, Windows, and most consumer electronics.
The block-count parameter specifies filesystem size in 1024-byte blocks. When omitted, the tool fills available device space. FAT type is automatically selected based on filesystem size unless explicitly specified with -F.
FAT filesystems use a file allocation table to track cluster allocation. Multiple copies of this table (default 2) provide redundancy. The filesystem remains widely used for USB drives, SD cards, and EFI system partitions due to its universal compatibility.

-F _fat-size_

Specify FAT type: 12, 16, or 32 bit; auto-selected based on size if omitted

Set volume label; maximum 11 characters

Set 32-bit hexadecimal volume ID

Number of file allocation tables; default is 2

Sectors per cluster; must be a power of 2

Logical sector size in bytes (512, 1024, 2048, 4096, 8192, 16384, or 32768)

Check device for bad blocks before creating filesystem

Read bad blocks list from file

Number of root directory entries; default 112-512 depending on FAT type

Number of reserved sectors; default 1 for FAT12/16, 32 for FAT32

Disable alignment of data structures

Toggle Atari filesystem variant

Create image file instead of using device; requires block-count

Verbose output mode

Location of backup boot sector for FAT32

BIOS drive number; 0x80+ for hard disks, 0x00-0x7F for floppies

Ignore safety checks; required for superfloppy format disks

Volume names are limited to 11 characters. The tool does not create bootable filesystems. It refuses to format partitioned devices by default; use -I to override this safety check for superfloppy format disks. FAT32 cannot store files larger than 4GB.

The FAT filesystem was developed by Microsoft starting in 1977 for standalone Disk BASIC. FAT12 appeared with MS-DOS 1.0 in 1981, FAT16 with MS-DOS 3.0 in 1984, and FAT32 with Windows 95 OSR2 in 1996. The mkfs.fat utility is part of the dosfstools package maintained for Linux.

mkfs(8), fsck.fat(8), fatlabel(8)