Convert OS X Lion DMG Installer to a Bootable USB Thumb Drive

This recipe will explain how to make a USB Thumb Drive bootable with the OS X Lion Developer Preview installer on it and in turn allow you to install Lion on a Mac without an optical drive (ie Macbook Air line).  We will need a copy of the installer dmg (not provided) and a 4GB USB Thumbdrive or Memorycard Reader w/memory card and a Mac to convert the dmg to a bootable usb thumb drive.


  • – OS X Lion installation DMG (hint: file named: mac_os_x_10_7_11a390.dmg)
  • – Mac running OS X Leopard or Snow Leopard
  • – USB Thumbdrive or Memorycard Reader w/memory card (4GB mininum, data will be destroyed).

This guide lets you restore the .dmg installer file for OS X Lion onto a usb thumbdrive. We can then boot the USB Drive on our Mac to install OS X Lion from it.  This is very handy for us Macbook Air users that do not have an external optical drive.


1. On your Mac, open up Disk Utility.  Click on the USB Drive on the left.

2. On the right pane, go to the Restore tab.

3. Click on the Browse button and locate the .dmg installer for OS X Lion. (ie mac_os_x_10_7_11a390.dmg)

4. Once you have it chosen, click and drag your USB Thumbdrive from the left pane to the Destination box. (ie THUMBDRIVE in the screenshot) and then click Restore

I recommend erasing the destination, so be sure to backup any data on the thumbdrive prior to this step!  This will take a few minutes to do.  Once its finished, you now have a bootable OS X Lion install thumbdrive (basically just like what the Macbook Air ships with).

5. Hold Option/Alt after your see the Apple logo appear and boot with the thumbdrive in your Mac.

Choose the USB Drive to install OS X Lion from your USB Thumbdrive!


– I have confirmed this working on a Macbook Air 11″, 2010, 1.6Ghz version.


About Jimmy Selix

Jimmy Selix is an early adopter that loves to be one of the first on the block to have the latest and greatest in technology and gadgets. Another love of his is being able to share his knowledge to others seeking it. Feel free to drop any comments or questions that you may have.
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The Conversation

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  • Dart Vader

    It’s possible to install 10.7 from the disk image: no need to make a USB Thumbdrive or DVD. Mac OS X Lion will probably be sold through the App Store.

    • hmm, i have not tried. I can give it a try this weekend! Not sure if you could install to a secondary partition though. i’ll see i guess 🙂

      • Dart Vader

        The DMG can be on the same partition, on another partition, on a USB or FireWire drive, on a networked volume… it doesn’t matter (I have tried same partition and AFP networked volume). It really does look like the OS will be sold through the App Store and will be installed as if it was any other piece of software on your computer.

  • How much space would you need on a flash drive?

    • romadu

      3.84GB, so it will fit on 4GB stick

      • I have a 4GB stick, but it won’t work!

        • Geek

          make sure you formatted as non-journaled.

  • Brad

    how do you boot the flash drive if youre using a macbook pro quad ? 

    • just be sure to have the drive plugged in and hold Option key right after you see the white apple screen pop up on boot.  You should then have the USB drive as an option. 

  • andsien

    Hi i get and error…its say “..cannot restore, cannot allocate memory…”

    im using kingstone USB 8 gb


  • skilla

    i locked my macbook pro. how can i unlock? wont let me do anything an i have no disks

  • jithu

    I have the compaq persario f700 laptop.

    system config
    – AMD Athlon 64 X2 Dual Core tk57 ) sup
    -Core Speed 1.8 Ghz
    -2.5GB DDR2 RAM Dual Channel clocked at 667mhz
    -Nvidia GeForce Go 6100 – Allocated VRAM
    -320 GB SATA HDD
    -windows 7 ultimate

    we like the install mac os x10 ,this os supported for my laptop Would you tell me suggestion for the Mac OS and supported or not for this notebook?

    Look forward to hearing from you. Thank you so much.

  • furqanmasmin

    thanx dude..its really work perfectly on my macbook pro 15 inch i5 mid 2010…im just beginner about mac…