Is there an industry standard file system cards are formatted with (when you first get them, and/or after a camera formats them)? FAT32, FAT16?


4 Answers 4


They're formatted with FAT16 or FAT32 (FAT32 is required for card sizes >2GB), and have a fairly specific (though simple) directory structure something like this:

ROOT --- DCIM -+- ###ABCDE
               +- ###ABCDE

### is from 100-999, and need not be consecutive. ABCDE is free text.

This structure won't be recreated if you format on a computer, but an in-camera format will usually construct it (or it will be built as required on a blank card).

There are similar standards for file names, and it's all specced out in detail by the Design Rule for Camera File System, which you can read in full here (PDF):


Such cards are usually formatted as FAT32 or exFAT, as that is nearly a universally compatible format at this point. It might depend on what kind of memory card you are referring to...SDHC, CF?

  • \$\begingroup\$ could be me, but I've seen FAT16 or exFAT use much more than FAT32. (when formated by the camera) \$\endgroup\$ Commented Aug 23, 2010 at 19:34
  • \$\begingroup\$ exFAT is really just an extension to the baser FAT32 that increases disk size, removes limitations, etc. It uses larger numbers to reference sectors, file sizes, etc. I guess its important to make the distinction. I've never seen FAT16, as it would only be useful for extremely small card sizes of 1Gb or less. \$\endgroup\$
    – jrista
    Commented Aug 23, 2010 at 20:12
  • \$\begingroup\$ FAT16 had fewer patent issues so it was preferred for the smaller cards. \$\endgroup\$ Commented Aug 23, 2010 at 21:30
  • \$\begingroup\$ Gocha. I don't think I've ever used a card smaller than 4Gb, and most of mine are 8 or 16gb. \$\endgroup\$
    – jrista
    Commented Aug 24, 2010 at 4:51
  • 3
    \$\begingroup\$ I've still got a 32 Megabyte CompactFlash card from an old digicam, still works on my latest DSLR but only holds 3 photos :-O \$\endgroup\$
    – Matt Grum
    Commented Sep 28, 2010 at 16:09

The SD standard formally requires

  • FAT16 for regular SD cards
  • FAT32 for SDHC
  • FAT64 ("exFAT") for SDXC

those formats are indeed to be used by the in-camera format function.

The latter choice has long been under fire by open source activist both due to strict licensing of the exFAT specifications - thus its poor support on anything that's not a recent Windows, Mac OS X or embedded system - and due to it being an allegedly less safe system (saving only one copy of the directory index) although this weakness is less critical on a write/read/reformat workflow as suggested by most camera manufacturers, and followed by pros and amateurs who don't keep their photos for future in-camera playback.

  • \$\begingroup\$ Since August 2019, exFAT has been released as an open standard. \$\endgroup\$
    – gparyani
    Commented Oct 2, 2020 at 4:30

Use FAT32 if you can, since FAT16 is becoming rare and fewer computers support this mode

  • 1
    \$\begingroup\$ Really? FAT16 is still supported by Linux and Windows 7, and is still used on lots of embedded devices, I don't think it's going anywhere soon! \$\endgroup\$
    – Matt Grum
    Commented Sep 28, 2010 at 15:29
  • \$\begingroup\$ Quick update: In 2020, FAT16 is still supported by all OSes. \$\endgroup\$
    – toriningen
    Commented Aug 12, 2020 at 15:22

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