Make volumes exact sizes?

Discussion in 'macOS' started by The General, Jan 15, 2009.

  1. The General macrumors 601

    Jul 7, 2006
    How can I make volumes exact sizes? I've noticed that when changing the size of my partitions with Disk Utility, the size of the partition actually ends up being .12GB smaller than what I set it to be. So if I type 300.00 in, the partition ends up being 299.88. If I type 300.12 in, it ends up being 299.88. If I type 300.13 in, it ends up being 300.01. If I type 360.12 in, it ends up showing 360.00 in Disk Utility, but on the desktop when I have show item info turned on it says 359.99GB.

    What do I have to do to have my partition be an exact size? Really? Is it really that difficult a task?
  2. VPrime macrumors 68000


    Dec 19, 2008
    London Ontario
    It is usually off by a little bit.. because of how many bits(8) are in a byte, byte in a mb, mb in a gig etc...

    40gb is actually 40,960(ish)mega bytes.. so thats where you get your extra numbers.
  3. The General thread starter macrumors 601

    Jul 7, 2006
    That's not the problem at all. I tell Disk Utility exactly how many gigabytes I want the volume to be, then it makes the volume, but the size is off by usually exactly .12GB, unless it would that .12GB would make the volume size end in .00GB, in which it reduces the size by .13GB so it ends in .99GB. It's whatever is inconvenient for me.

    Look, all I want is for this to show an even number:

  4. John Jacob macrumors 6502a

    John Jacob

    Feb 11, 2003
    Columbia, MD
    I could do that.. see the screen capture below. I don't remember exactly how I did it, though.

    Obviously, I could do it only for one partition. The other partition uses the remaining free space, so it ended up as an un-exact number. The only way to do it for both partitions would be to have unused free space.

    I suspect both of us have a touch of OCD. :D

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