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What cluster size should i use for fat32 USB sticks ?

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Mar 4, 2012
So about the allocation size I found this chart on a website and hoping it's correct.

4GB - 7GB = 4096 bytes (4K)
8GB - 15GB = 8192 bytes (8K)
16GB - 31GB = 16384 bytes (16K)
32GB - 63GB = 32768 bytes (32K)
64GB - 127GB = 65536 bytes (64K) and etc..................

So for example I have a 64GB USB stick, it's not actually 64GB, it's 63GB. So according to the chart I used allocation size 32768 bytes (32K).
I'm formatting to FAT32 by the way all my USB sticks of different sizes.

By the way I'm using a nice little free program to for my USB sticks to FAT32 cause Windows does not format in FAT32 higher then 32GB. When I bought my 64GB sticks from the factory they were FAT32 but since I formatted them to NTFS and then trying to put back to FAT32 Windows won't allow it. So that's why I'm using a 3rd party program.


Anyway the program defaults to what the chart is saying. The program defaults to 32768 bytes (32K) for a 64GB stick which is really a 63GB, just like I was saying above. I hope you understand what I'm trying to say. So for another example my 16GB is is really 15GB so I'm choosing to format using 8GB - 15GB = 8192 bytes (8K) and this is also what the program is defaulting to.

So does all this sound correct ?


Gulper Nozzle Co-Owner
Dec 15, 2008
Default? Never had an speed issues using that.

But I am interested to hear if there is something better...