Low End Mac Mailbag: “Easy Peasy” USB Standalone Installers for Mac OS X, OS X, MacOS

Fresh to the Low End Mac the mailbag from long time reader Adam Goff:

“I recently made the personal decision to “un-OCLP” a few of my Intel based Macs and thus prompted a desire to create an easy to follow guide for those who need to create install media on their Mac computers running Mac OS X Tiger and later.”

Editor’s Note:
For those who are not extremely familiar with OCLP, that acronym stands for OpenCore Legacy Patcher. OpenCore Legacy Patcher allows one to run later OSes than Apple intended on many of Apple’s Intel Macs.
“I certainly think (OCLP) is an amazing project, and I am in awe at the work that has gone into it, but the fact is – I only have two machines at this time that are officially supported by Apple’s current operating system. As a result, in order to make my other Intel machines more useful for my purposes (namely accessing a large library of 32-bit applications and bins full of now-unsupported peripherals), that would necessitate reinstalling older versions of the Mac OS… A task not quite as simple as it once was.”


The last version of Mac OS X Apple sold on an optical disk was version 10.6 Snow Leopard in 2009 (final retail version was 10.6.3) and the last OS Apple would ever release on any physical format was Mac OS X 10.7 Lion (as a USB installer) in 2011. All subsequent OS X/macOS releases have been digital download only. While this made a certain amount of sense with the widespread adoption of broadband internet throughout the 2000s, it presents an added layer of complication in the event one would need to reinstall or roll back their installation of the system software.

To Apple’s credit, they did introduce the Internet Recovery feature in 2012, but this method has caveats and limitations. First, it only applied to new Macs going forward (although some 2010-2011 Macs could be firmware updated to gain the feature). It also had (and still has) a tendency to be flaky, especially with older systems.

Editor’s Note:
You may not necessarily get the original OS that shipped with a given Mac at all and may wind up with the newest possible operating system from Apple that particular Mac can run instead.

Most importantly however, as the name “Internet Recovery” implies, it requires a fast, stable connection to the Internet – something that isn’t guaranteed 100% of the time. While Apple has thankfully provided installer images for 10.7 Lion through 10.12 Sierra through their support website, the multitude of sites providing directions for how to create a bootable installer are at best vague – if not flat out incorrect.

As a result, a lot of incorrect information ends up getting passed around to those looking for clear and straightforward directions on how to do so. In an effort to rectify that situation, I spent the past week testing various methods on different systems that one may have available to them and have streamlined the steps necessary to create bootable installers of Mac OS X/OS X/MacOS on systems running OS X 10.4 Tiger (PPC/Intel) through MacOS Sonoma.  I even reviewed and chronicled the steps required for creating Mac OS X/OS X/MacOS install media on Windows 10/11, and the free utilities needed to do so.

Creating Bootable Installers on Mac OS X/OS X Versions 10.4 – 10.8
Before you get started, you’ll need an appropriately sized USB stick (16GB to be safe) and the most up-to-date browser your system can handle in order to download the installers from Apple. For downloading these installers on PowerPC systems I would recommend InterwebPPC. For downloading these installers on Mac OS X 10.6.x (Snow Leopard) – Firefox Legacy is an excellent option (search “Nightly” 52.9.1), and for Mac OS X 10.7.x (Lion) and OS X 10.8.x (Mountain Lion), Chromium Legacy provides a good option. I personally tested all of these browsers on systems that can run these operating systems, and as of November 2023 all could access and download the installers from the Apple Support page previously mentioned.

Follow these steps to create install media from within Mac OS X/OS X 10.4.x – 10.8.x:

  1. Download your installer of choice directly from Apple. *Do not download these installers from any other third party website as the integrity of them cannot be vouched for.
  2. Download and install the free utility The Unarchiver (click on the link for earlier versions since these steps are for versions of Mac OS X/OS X prior to OS X Mavericks 10.9.x)
  3. Double click the file “InstallMacOSX.dmg” to mount the image. Once inside of the volume, you will see a file called “InstallMacOSX.pkg.”
  4. Right click InstallMacOSX.pkg and click “Open with… Other” Navigate to and select The Unarchiver (Alternatively, you can launch The Unarchiver and select File -> Unarchive to… (location of choice). I typically create a new folder on the desktop to extract to for easy navigation.
  5. Inside the desktop folder you created, you’ll find another folder called “InstallMacOSX” and inside that you’ll find a second file called “InstallMacOSX.pkg.” However, when right clicking this second .pkg file you will be presented the option to “Show Package Contents.”
  6. After clicking Show Package Contents, you will now see a file called “InstallESD.dmg” – this is the actual bootable image you need to flash to your USB drive. Also drag this file to your desktop for easy navigation.
  7. Open the Disk Utility application, insert your USB drive, and drag the “InstallerESD.dmg to the sidebar of Disk Utility.
  8. Highlight your USB drive and select “Restore.” Drag the InstallerESD.dmg file to the source field. Click apply to flash your drive from the installer image.
  9. Once completed, insert the USB to the Mac you wish to install to snd boot holding the “Option” key. You should be presented with the option to continue booting from the USB.

If doing this to a computer that previously had High Sierra 10.13+ installed to it (with APFS), you’ll need to boot using Recovery mode (holding Command-R during the boot sequence after power on) and first reformat your drive back to MacOS Extended Journaled (with HFS+) and then reinstall through Recovery from the USB. If for whatever reason the machine will not access the install media from the USB in Recovery mode, after reformatting you can then use the Recovery Disk Utility to flash the installer from the USB to a small partition on the drive just large enough to fit the installer and then boot from that.

Creating Bootable Installers in OS X/MacOS 10.9 and Later
Creating USB installers on OS X Mavericks and later are largely similar to what’s required for earlier versions of Mac OS X/OS X, but with the addition of the fantastic free utility balenaEtcher.

Follow these steps to create install media from within OS X 10.9 through current builds of MacOS:

  1. Complete steps 1 through 6 of the previous section that covers creating install media in Mac OS X/OS X versions 10.4-10.8.
  2. Download and install balenaEtcher from the link above and insert your USB drive.
  3. In balenaEtcher, select Flash from File and choose the “InstallESD.dmg” file on your desktop. You will get a warning about missing partition tables, ignore this warning and continue.
  4. Click Select Target and choose the USB drive you are using, then click Flash and let the application work its magic.
  5. Once the installer has finished being created, insert the USB drive into the target Mac and boot holding the [Option] key, and the installer should present itself.

On systems 10.6+ the use of The Unarchiver utility is not 100% required (in these versions of Mac OS X/OS X/MacOS, utilities are built into the operating system to expand the initial “InstallMacOSX.pkg.” For those wishing to avoid downloading an additional piece of software, perform the following steps as an alternative to using The Unarchiver utility:

  1. Open your Terminal.
  2. Type the following:
    pkgutil —expand ~/Desktop/Expandedpackage
  3. Hit enter and enter your password if requested.
  4. The package will be expanded into a new folder on your desktop call “Expandedpackage.” From there, you can pick up from step #5 of the previous section.

Creating Bootable Installers For Mac OS X Within Windows 10/11
Many of us also have Windows computers in our setups that we use in conjunction with our Macs for a variety of reasons (Editors Note: Some also may use Windows on a Mac on a separate drive or partition via Boot Camp or straightforward EFI installations). If one desires to create a Mac OS X/OS X/MacOS installer from within Windows 10 or Windows 11 for any reason, the process is just as straight forward as it is with creating the installers within Mac OS X/OS X/MacOS. This method was tested using a Lenovo Thinkstation P720 running an up-to-date Windows 11 installation.

This method requires access to a Windows Computer or a Mac already running Windows via Boot Camp or EFI on a Separate Partition or Drive.

Perform the following steps within Windows 10 or Windows 11:

  1. Download a Mac OS X Lion (through MacOS Sierra) Installer .dmg file from the Apple website.
  2. Download and use PowerISO for Windows (the trial version works just fine) and open the Installer.dmg file.
  3. Double click the .pkg file that is shown – it will automatically expand into PowerISO’s user temp folder.
  4. Locate the expanded .pkg file and open it in a program such as BreeZip. Double click the “InstallMacOSX.pkg” folder.
  5. Drag the “InstallESD.dmg” image to the desktop.
  6. Download balenaEtcher for Windows to flash the .dmg file to your USB drive. The Windows version behaves exactly the same as the Mac version. **As long as the USB drive is recognized and mountable in Windows, you do not need to worry about any formatting of the drive. Ignore missing partition table warnings as before.
  7. Once done, eject the drive and insert it into the Mac you wish to install this version of Mac OS X/OS X/MacOS on (boot holding the [Option] key to invoke the boot picker). The installer should present itself.

Conclusion/Closing Notes

I repeated these steps several times with several installers on different systems and was able to reproduce identical, bootable Installer USB drives each time. With a large enough, pre-partitioned USB drive, it is possible to install multiple OS X installer versions with balenaEtcher onto a single USB stick.

I hope everyone finds this information helpful when looking to reinstall old versions of OS X on to their era-appropriate systems! Thanks for reading!

Closing Editor Comments:

  1. In Mac OS X/OS X/MacOS from Mac OS X 10.7 through MacOS Catalina, yet another method exists using the utility named DiskMaker X.  Adam’s method above is a little more versatile, but DiskMaker X has proven to be a straightforward method as well for quite some time.

  2. This guide covers creating install media from a variety of Mac and Windows systems using Apple’s provided digital installer files (which start with Mac OS X Lion), and while Mac OS X Snow Leopard and earlier versions of Mac OS X shipped on a physical optical disc (ensuring a clean way to downgrade or reinstall that operating system on the Macs that can run those installers), some individuals have decided to forgo optical discs on older Macs in favor of optical bay drive adapters for additional storage.  

    While USB external optical drives can be used as bootable sources on Intel Macs (also possible on PowerPCs with some OpenFirmware commands to enable it), and while FireWire optical drives (and FireWire Target Disk Mode) can be used between Macs equipped with FireWire that can run these older versions of Mac OS X, making your own backup digital installers is not a bad idea as discs get get scratched, warped or ruined in other ways and naturally degrade over time.  Even when optical drives have not been swapped out for alternative storage, optical drives still fail, so it’s wise to always have all bases covered to restore those old Macs.  Low End Mac will soon provide a how-to guide for making good digitized backups of legacy optical media of Mac OS X (from 10.0.x through 10.6.x) and how you can use this media to restore your older Macs.