I am helping my in-laws install Lion this weekend. They have purchased the Lion USB upgrade, but are only running Tiger on their Mac. Is the Lion USB bootable so I can do a clean install rather than upgrading their OS?

  • 1
    Big caveat - make sure the machine you are upgrading meets the Lion system requirements, namely, that you have a Core 2 Duo processor or better. Tiger was released during the PowerPC transition and thus the first generation of Intel Macs, so just be sure to double check that your system is supported. Oct 21, 2011 at 14:42
  • @chriSanderson thanks for the heads up. I've checked the machines specs and they meet the minimum requirements.
    – ahsteele
    Oct 21, 2011 at 15:08

3 Answers 3


Yes. You can boot from the USB drive. This means you can avoid having to get 10.6.8 and the Mac App store to download the Lion installer but can instead boot from USB and erase the drive and perform a bare install.

Things to remember:

  • Lion does not ship with iLife so consider pricing that or checking if older versions of the suite will work as desired.
  • Lion may not import settings from older backups as well as it does in Snow Leopard, but it's easy to try and erase and start over if problems arise.
  • You can always hand copy files and folders or make a bootable clone of the old system just in case you will want to boot the mac in the old OS to export some data you didn't know needed moving (old tax programs, etc...)
  • Do I need to do anything else other than plug the drive in or I need to hold some keyboard combination on boot?
    – ahsteele
    Oct 21, 2011 at 17:05
  • If just plugging in doesn't work (it might) you can hold alt to select the boot drive.
    – voidStern
    Oct 21, 2011 at 18:22

Yes, technically Lion is an upgrade from Snow Leopard, from a licensing perspective, but frankly there are no technical limitations and you can happily full-install it on a fresh drive, or even on a drive that used to have XP on it, it doesn't care in operation, and will happily allow you to use disk utility to prepare any old partition (within reason, bearing in mind that it also installed a recovery partition which can cause issues if you have more than 3 existing partitions) for install without caring what else is kicking around.


Yes, the Lion flash drive from Apple will boot Macs capable of running Lion.

Or, had you not bought the Apple flash drive you could upgrade a single machine via the web download but before running the installer, use that disk image to create your own Lion flash drive:


I upgraded my wife's MacBook Pro with the flash drive I made from the download I bought for my computer. And, I now have a "stick" that will boot our Macs and any new Mac I buy. I also saved the original disk image on a backup hard disk so I can use it to make another "stick" if god forbid I misplace the one I made.

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