A bootable USB stick with macOS is handy when you want to put macOS on an erased drive, install several Macs without downloading each time, or when your Mac's Recovery mode does not work. This article explains how to make such a bootable USB stick and how to start your MacBook from it.
Blue Apple repairs MacBooks in Amsterdam. If your Mac does not recognise the stick on any port, a port may also be the cause; more about that at the end.
What do you need?
- A USB stick of at least 16 GB (32 GB for the newest versions). Everything on the stick is erased.
- A working Mac with internet.
- The installer of the macOS version you want. Apple has a page on its support site with links to recent and older versions.
- For a MacBook with only USB-C: a USB-C stick or an adapter.
Step 1: download the installer
Download the version you want via the App Store or Apple's site. The installer goes into the Applications folder, with a name like "Install macOS ...". Do not run it; if it opens by itself, quit it with Command + Q.
Step 2: prepare the stick
Connect the stick, open Disk Utility, select the stick and click Erase. Choose Mac OS Extended (Journaled) as the format and GUID Partition Map as the scheme. Give it a simple name, for example MyVolume. More about formatting in formatting a USB stick on a Mac.
Step 3: make the stick bootable
- Open Terminal.
- Type the createinstallmedia command with the path of the installer and the name of your stick. Apple lists the exact command per macOS version on its support site; copy it and only change the stick's name.
- Press Return and enter your password. You see no characters while typing.
- Confirm with Y that the stick may be erased.
- Wait until Terminal reports it is done. That can take a quarter of an hour or longer.
Step 4: start up from the stick
- Mac with an Apple chip: connect the stick, shut the Mac down, hold the power button until you see the startup options, choose the stick and click Continue.
- Intel Mac: hold the Option key during startup and choose the stick. On Intel Macs with the T2 chip you may have to allow booting from external media in Startup Security Utility.
You then get an environment similar to Recovery mode. There you can use Disk Utility and install macOS.
It does not work
- The stick does not appear in the startup options: try another port or adapter, and another stick. Cheap sticks do not always work.
- "Cannot be verified": download the installer again; it may be damaged or outdated.
- The Mac says the version does not fit: a Mac cannot run an older macOS than the version it shipped with. See macOS versions at a glance.
When do you need this?
For most people Recovery mode is enough to reinstall macOS. A stick is mainly handy with a slow or no internet connection, when going back to an older version (see installing an older macOS), or when Recovery itself no longer starts.
What we do at Blue Apple in Amsterdam
If your Mac does not start even from a good stick, or the internal drive does not appear in Disk Utility, it may be a hardware problem, such as a faulty SSD or logic board. Also if no USB port recognises a stick, we test the ports. More on our pages about MacBook port repair and MacBook repair in Amsterdam.
Frequently asked questions
Can I make a bootable stick on Windows?
Not the official way; you need a working Mac.
Does one stick work for several Macs?
Yes, for all Macs that support that macOS version.
Do my files stay if I install from the stick?
Only if you do not erase the drive first. Always make a backup before you start.
