How to create a bootable macOS Catalina installer drive

An external drive that you can use as an installer for macOS Catalina is a handy thing to have. If you have multple Macs to upgrade, it’s a lot more efficient to plug in the USB installer drive and run the installer than to log into the App Store, download the 6.5GB OS installer, and then run it.

In this article I’ll go over the different ways you can create a bootable macOS Catalina installation drive. But before I give instructions on how to create the drive, I’ll go over the items you’ll need and how to get them.

Macworld also has bootable-install-drive instructions for:

  • Mojave (macOS 10.14)
  • High Sierra (macOS 10.13)
  • Sierra (macOS 10.12)
  • El Capitan (OS X 10.11)
  • Yosemite (OS X 10.10)
  • Mavericks (OS X 10.9)
  • Mountain Lion (OS X 10.8)
  • Lion (OS X 10.7)

Get an external drive and maybe an adapter

The macOS Catalina installer software is nearly 6.5GB, so you need a USB external drive that can hold that much data. The drive can be a thumb drive, hard drive, or SSD.

If you want to use a thumb drive, an 8GB drive works perfectly. I used an 8GB Kingston Data Traveler G4 ($7 on Amazon); it’s cheap and it supports USB 3.1, so it’s fast. I’ve also used older USB thumb drives that support USB 2.

externl usb mbpIDG

A VisionTek USB drive coneccted to a 2017 MacBook Pro via Apple’s USB-C VGA Multiport Adapter ($69).

If you have a 2015 or newer MacBook or a 2016 or newer MacBook Pro, you may need Apple’s $19 USB to USB-C adapter. This will allow you to connect a storage device that uses a USB type-A connector. If you don’t have an external drive and you have a USB-C Mac laptop, you could buy the SanDisk Ultra USB Type-C Flash Drive, which has a USB-C connector. You can get model number SDCZ450-016G-G46Remove non-product link.

When creating the boot drive, the storage device is reformatted, so there’s no need to format the drive beforehand.

Get the macOS Catalina installer software

The macOS Catalina installer is available in the App Store. If you launch the App Store app, do a search for “Catalina.” Or, if you click this Catalina App Store link, it will take you to the Catalina App Store webpage, then click on the “View in the Mac App Store” button. 

You can read the information to learn more about Catalina. When you’re ready to download the software, click the Download button under the icon on the upper left. (If you’ve already downloaded the installer, the button will say Install instead of Get.)