If your Mac suddenly refuses to boot up properly, you might need a bootable macOS USB installer to make repairs. But how do you create such a disk if all you're left with is a Windows 10 computer? Fortunately, there's a great tool that you can use for free to create bootable macOS media on a USB drive in a Windows 10 environment. This article shows you how to download a macOS DMG file, format a USB drive using a GUID Partition Table, burn the DMG to the drive and boot your Mac from the USB. All the steps except the last one are done on a Windows 10 machine.
If you want to use your USB stick with an Apple Mac, you will need to restart or power-on the Mac with the USB stick inserted while the Option/alt (⌥) key is pressed. This will launch Apple’s ‘Startup Manager’ which shows bootable devices connected to the machine. Your USB stick should appear as gold/yellow and labelled ‘EFI Boot’. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing. Turn on your Mac and continue to hold the power button until you see the startup options window, which shows your bootable volumes and a gear icon labled Options. A macOS Catalina USB install drive is a great tool to have on hand to for quick and easy macOS 10.15 reinstalls. We show you how in this video tutorial. How to create a bootable macOS Big Sur USB install drive. Step 1: Download macOS Big Sur. After Big Sur launches later this year, you’ll be able to download it directly from the Mac App Store. Related: How to Create macOS Catalina USB Installer – Hackintosh Creating a bootable USB installer can be done in different ways. Just like we’ve previously shown a few ways to create macOS Catalina USB installer which would work probably for Mac and Hackintosh even.
Part 1: Download macOS or Mac OS X DMG File
The first step is to get the DMG disk image file for the version of macOS that you want. You can get a copy of the latest macOS version from Apple download portal or App Store here. There are also several other direct download sites that offer various versions of Mac OS X in DMG format rather than the standard APP format that runs on Mac. Since you're working in a Windows environment, you need the DMG rather than the APP file.
macOS DMG Download Link:
Part 2: Format USB Drive to GPT (Optional)
Updates (Dec 8, 2020): The latest version of UUByte DMG Editor is able to format the USB automatically, so this part is optional. Follow the steps only when the burning process failed in Part 3.
Mostly, the USB drive was formmated to FAT32 in default when being shipped out from the factory. However, FAT32 can be only used for installing OS with legacy BISO, which doesn't work for macOS. So the next step is to format your USB drive in the GPT partition style in order to burn installation files to the desired USB drive. You can do this in Command Prompt as admin. In elevated Command Prompt (Ctrl+Shift+Enter), input the following series of commands followed by Enter after each line:
Diskpart
List disk
Select Disk X (X stands for the USB drive name that appears after the previous command)
Clean
Convert GPT
Create partition primary
Part 3: Create Bootable macOS USB from Windows 10/8/7 PC
You have now formatted the partition of USB drive. It's time to download UUByte DMG Editor for Windows. Although this is a premium software, you can use the initial free trial period to create a bootable macOS USB on Windows 10. After installing the application, follow the sequence of steps shown below:
Step 1: Right-click the software icon on desktop and select 'Run as Administrator' from the contextual menu. Choose 'Run' when prompted.
Step 2: Insert your formatted USB drive, and click 'Burn' tab on the main screen.
Step 3: Click 'Browse' button to import macOS dmg file into the program. And select the USB drive name from the second row. You can also set a volume labe for that USB drive.
Create Bootable Usb Macos On Windows
Step 4: Click 'Burn' button at the bottom to start the process. You will see a progress bar and wait around 10 minutes to get it done.
Step 5: Once the progress bar is at 100%, a bootable macOS USB is ready. After that, you can use that USB drive for installing macOS.
Create Bootable Usb On Mac Software
This is one of the easiest way to create a bootable macOS USB on a Windows PC. The steps are simple and instructions are pretty clear.
Part 4: Boot Mac from macOS USB Drive for Installation
Now remove the USB drive and insert it into the Mac computer. To boot from the disk, you need to hold down the option key when you hear the boot chime. This will take you to the Startup Disk Manager, where you should be able to see the USB drive. It might have a different name, but as long as it is bootable, you'll be able to see it there. Once you select it, the computer will boot from the disk and the macOS installation will begin.
Conclusion:
The whole process might look a bit complicated if this is your first time, but just follow the instructions in this article and you should be fine. That being said, you need to be careful when downloading the DMG file and formatting your USB drive. If you don't do these two steps correctly, the output drive from the UUByte DMG Editor software won't be bootable, which means you can't install macOS from that USB drive, and you may need to do the whole thing over again.