Q306233

Also known as Extended File Allocation Table, Extended FAT

exFAT (Extensible File Allocation Table) is a file system optimized for flash memory such as USB flash drives and SD cards, that was introduced by Microsoft in 2006. exFAT was proprietary until 28 August 2019, when Microsoft published its specification. Microsoft owns patents on several elements of its design.

Key facts

Filesystem.name: exFAT
Filesystem.developer: Microsoft
Filesystem.full_name: Extensible File Allocation Table
Filesystem.introduction_os: Windows Embedded CE 6.0
Filesystem.directory_struct: Table
Filesystem.file_struct: bitmap, linked list
Filesystem.bad_blocks_struct: Cluster tagging
Filesystem.max_volume_size: 128 PB, 512 TB recommended
Filesystem.max_file_size: 128 PB
Filesystem.max_files_no: up to 2,796,202 per directory
Filesystem.max_filename_size: 255 characters
Filesystem.filename_character_set: all Unicode characters except to and (encoding in UTF-16LE)

~10 min read

Article

17 sections

Contents

History
Features
Efficiency
Adoption
Technical specifications
File name lookup
File and cluster pre-allocation
Directory file set
Metadata and checksums
Flash optimizations
Other implementations
Legal status
List of implementations
See also
Notes
References
External links

exFAT can be used where NTFS is not a feasible solution (due to data-structure overhead), but where a greater file-size limit than that of the standard FAT32 file system (i.e. 4 GB) is required.