I have a 4.04GB DMG file for Mac OS X 10.8 (Mountain Lion), which is being used for reinstalling the OS on my MacBook Pro.

However, the bootable USB needs a GPT (GUID-partition table) format. The only compatible format is FAT32, which supports a maximum of 4.00 GB per partition.

Is there any way to compress the DMG file to be smaller than 4GB, or booting from an ISO file?

I'm using Windows 7 on an HP Pavilion laptop. The .img file is 4.04 GB, and I need to copy that file to a USB stick that supports it. What format should I use in my 32 GB SanDisk USB stick while on the Windows 7 computer in order to read/write?

  • What OS were you thinking of creating a bootable USB on? – JakeGould Sep 11 '15 at 5:14
  • I'm creating the bootable USB on Windows 7. I have the .dmg file here. – Alfredo Barreto Sep 11 '15 at 5:26
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    possible duplicate of Create a bootable USB drive from a DMG file on Windows – JakeGould Sep 11 '15 at 5:27
  • Nope. The thing here is that the DMG file is 4.04 GB, and it needs to be smaller than 4.00 GB to be supported in a FAT32 USB stick. – Alfredo Barreto Sep 11 '15 at 5:30
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    The bootable USB needs to be GPT. Your concept it should be FAT32 makes no sense since FAT32 requires MBR. Please read that thread again. You can definitely do this, but you need to get over the FAT32 desire. – JakeGould Sep 11 '15 at 5:32

simply format your boot USB Stick with exFAT which can handle >4GB files fine and will be recognized by UEFI (and BIOS). just tested with and quite old MacBook Air

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