What are the theoretical and practical minimum sizes for a FAT16 volume?

I'm trying to determine the smallest Flash-chip size that can handle a FAT16 FS.

2 Answers 2


If I remember correctly it's 4.1MiB (1,048,576 bytes*4.1 = 4,299,161.6 bytes).

  • That's correct. It is either 4.1MiB or equivalently 4.3MB. If you would also like the max size, it is (on a NT/2000/WinXP machine) 4GiB or 4.29GB.
    – Marcin
    Nov 23, 2009 at 19:06
  • Ah! So it makes sense that my FAT driver throws error at about 4MB. Where does the 4.1 come from?
    – MandoMando
    Nov 23, 2009 at 20:13
  • The minimum number of sectors is 8401, so the correct minimum byte count (sector size = 512 bytes) is actually 4,301,312. That gives 4.10205078125 MiB.
    – monkey0506
    Feb 2, 2016 at 18:15

4.1 MiB is correct, however you could go smaller with FAT12, which is still readable by modern OS's.

  • I would, though I hear implementing a FAT12 driver is not easy.
    – MandoMando
    Nov 23, 2009 at 20:14

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