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Every year Apple releases a brand spanking new version of its Mac operating system, introducing new features and improvements. These updates are free, and you can even hop on the annual public beta if you’re really keen.
But what if you have a few Macs in your household, and don’t fancy downloading gigabytes of installation files multiple times? One thing Apple doesn’t tell you is how to save the installer, and why you might want to do so.
Fortunately it’s really easy to do, and handy even if you only have the one Mac.
Why Save The Installer?
The most obvious reason you’ll want to save the installer is because of its size. As you’re downloading the whole operating system, rather than an incremental update, the update can be pretty big. macOS Sierra is a 4.88GB download, which is just over 80 minutes at a modest speed of 1MB per second.
Furthermore, if you like to jump on the bandwagon and download the update immediately as it becomes available, transfer speeds can take a tumble as everyone else does the same. When you finally get the installer down, rather than downloading it again on each Mac, you should save the installer instead.
This installation file may also be helpful in the future should something go wrong with your Mac, and you decide to “start again” and reinstall macOS. Despite what many Apple users believe, Macs aren’t infallible and macOS can fail at any time just like Windows can. There are many reasons your Mac won’t wake from its slumber, and often the easiest way is to reinstall the operating system using a USB stick.
It’s always best to make this USB stick in advance, assuming you don’t have another Mac in the house you can use when things go wrong. Keep in mind that if you have to boot into recovery mode to perform the reinstall process, you’ll need to perform this download anyway. It’s best to keep your Mac backed up with Time Machine, and keep that installer handy to save time.
Remember: If you have an older Mac that doesn’t support the latest version of macOS, you’ll need to keep the relevant installation file to hand when it comes to recovering your Mac. You can download this file on any new Mac provided you have it in your purchase history, just open the Mac App Store and hit Purchased.
Download macOS & Save The Installer
Launch the Mac App Store and head to the Updates tab to find the latest version of macOS. You can also find it by searching from it by name, and it also usually appears under Quick Links to the right of the Featured tab.
Download it as you would any other app, enter your Apple ID password, and wait for the process to complete. The installer will automatically launch once the download is complete, but resist the urge to install right away and close it.
Remember: macOS deletes the installer after you’ve used it, so make sure you’ve saved the installer before you update your current machine!
Find the installer file titled Install macOS Sierra (or whatever the current version of the OS is called) in your Applications folder. Copy this installer to a spare hard drive, use it to create a bootable USB stick, or AirDrop it to any of the other compatible computers in your household.
Place the Install macOS Sierra file in the Applications folder of any Mac you’d like to upgrade, and run it to perform the upgrade.
Before You Install
Installing a new operating system is a major upgrade, and though most installations will go smoothly there’s always the chance that something will go wrong. For this reason you should always back up your Mac with Time Machine before you update macOS, just in case.
There are precautions to take before you hit Install to minimize the chance of problems — running First Aid on your disk with Disk Utility, ensuring you have enough free space, or creating a USB drive in case things go wrong. We’ve got some guidance if your Mac gives up during the upgrade.
The whole installation process takes somewhere around 30 minutes, and when your Mac restarts, you’ll be able to start using your computer again.
Choose a Wi-Fi network, sign in with your Apple ID, and agree to the updated terms and conditions to begin using the latest version of macOS. You may also be asked to activate any new features included with the OS, as was the case with Siri on macOS Sierra.
Typically following any major install, you should check for updates via the Mac App Store, particularly as developers get a few months to prepare for the new features. Update any apps that don’t use the Mac App Store separately, most will detect an update and apply it if available. You’ll also want to plug in your Time Machine hard drive and set a new backup point.
Do you have a bootable USB installer tucked away in a drawer somewhere? And what do you think of the latest version of macOS?
Article updated by Tim Brookes on November 23, 2016.