[How to] Install OS X Mountain Lion on Multiple Computers

by: - Last updated on: December 16th, 2016


Apple has just released the Mac OS X 10.8 Mountain Lion and I’m sure many of you who own multiple Mac computers will be worrying about purchasing multiple licenses of Mountain Lion in order to install it on all your computers.

Well, don’t fret. The personal use license which came into effect from Mac OS X 10.7 Lion, permits users to purchase once and install the OS on all their computers authorized for personal use. So how to go about it?

If you have a good broadband internet & don’t have to worry about the bandwidth, then you can open the Mac App Store on your other Macs, go to Purchases tab and you can re-download Mac OS X Mountain Lion on each of your computers. For others, below are couple of options.

Install or Upgrade OS X Mountain Lion on More than One Computer

Method 1: File Sharing over the network

This is the simplest of the 2 methods we have. Assuming that you have both (or all) your Mac(s) on the same network, you can simply enable File Sharing to copy the installable.

  • Download Mac OS X 10.8 Mountain Lion from Mac App Store. Do NOT install it yet. This is because, Mac OS will delete the installer once the installation is complete.
  • On the source Mac, launch System Preferences and click on Sharing.
  • Enable File Sharing by clicking on the checkbox next to it. Close System Preferences.
  • Go to your Applications folder and look for “Install OS X Mountain Lion.app
  • Press Command+K to Connect to server and then click on Browse to find the other shared Macs.
  • Now on your shared Mac, navigate to Applications folder, and drag & drop the Install Mac OS X.app file.
  • Once the file is copied, launch the installer to upgrade to Mountain Lion.

In case your Macs are not on the same network, check out the alternate method.

Method 2: Copying to External Storage

This method involves copying the Mountain Lion installable onto an external storage device like a USB stick or a DVD drive. Mind you, the OS X 10.8 installable is almost 4.05GB, so you need to have a storage bigger than that (at-least 4.25GB).

  • On the Source Mac, open Applications folder and look for “Install OS X Mountain Lion.app
  • Plug in your external storage device and copy/burn the installable onto it.
  • Disconnect the external storage from the source Mac and plug it into the recipient Mac. Copy the “Install OS X Mountain Lion.app” onto the Applications folder of this Mac.
  • Launch the installer and upgrade to Mac OS X Mountain Lion.

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  1. can I use an external hard drive to save the installer or does it have to be DVD or USB stick?

  2. Isn’t it possible to simply re-download it from the App Store with the same AppleID you used for the original purchase? It seems like a much easier option than having to go through the trouble of stopping the installation and transferring files and all that whatnot.

    1. Yes, of course. But not anyone will have the bandwidth to afford that (considering it’s 4GB+). Foolish of me not to mention that in the article. I’ll update right away

  3. Also something that you left out that might be easier for some people. If the computers all have Lion installed on them, just open finder and click on AirDrop on the left. The finder windows on the other computers need to have AirDrop opened as well to be seen in the grid. After you see the computer/s you want to install ML on as well, just drag the installer onto those computers and the accept them on the other end. Took about 15 – 20 min. to send the file this way. just make sure your wifi is on. Doesn’t even need to be on the same network. They just need to be in the same vicinity.