If you’re still using a Mac OS X the time will come when your computer won’t boot, or a problem may arise where you can’t take control of the device, and booting from an OS X installation media will be required.

• Use these steps to set up a USB drive with a GPT partition: Open Start on Windows 10. Search for Command Prompt, right-click the top result and select the Run as Administrator option. Type the following command to open Diskpart and press Enter: diskpart. Type the following command to determine the.
• Step 1: Right-click the software icon on desktop and select 'Run as Administrator' from the contextual menu. 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.

Creating the bootable OS X El Capitan installer will erase the USB flash drive you're using. Before you proceed, make sure you have a backup of the flash drive's contents or that you don’t care that the data will be erased.

This is why it’s recommended that you make a Mac OS X bootable USB when your Mac is in working conditions. However, if you find yourself on a scenario where your device (iMac, MacBook Pro, Air, Mac Pro or Mini) is not responding and you happen to have a Windows 10 device, then you can still be able to make a USB bootable installation media for your Mac OS X to reinstall the operating system using the Recovery Assistant.

These instructions will also work for Windows users who are running Mac OS X on a virtual machine and need to upgrade to the latest version. For instance, to OS X Yosemite.

Requirements

Before you dive into this guide, you’ll need a few things:

• A broken Mac computer with Mac OS X.
• A trial copy of the TransMac software.
• One high quality USB flash drive with 16GB of storage.
• A copy of Apple’s macOS (DMG file).

Now that you have all the necessary ingredients, you’re ready to make a Mac OS X bootable USB using the DMG file of the operating system with the steps below.

Create Mac OS X bootable USB installation media

Before you can use TransMac, you first need to partition your USB flash drive with a GPT partition, as a normal MBR partition may not work. To do this, you’ll need to use the Diskpart command-line utility on Windows 10.

Setting up GPT partition

Use these steps to set up a USB drive with a GPT partition: Simple tableadd a table to your website.

1. Open Start on Windows 10.

2. Search for Command Prompt, right-click the top result and select the Run as Administrator option.

3. Type the following command to open Diskpart and press Enter:

4. Type the following command to determine the USB flash drive and press Enter:

5. Type the following command to select the storage and press Enter:

   Quick tip: The select disk 1 command as an example, but you have to replace 1 with the number of the flash drive you want to use.

6. Type the following commands to delete everything from the USB thumb drive and press Enter:

7. Type the following command to convert the drive into a GPT partition and press Enter:

8. Type the following command to select the new partition and press Enter:

After you complete the steps, the USB flash drive from MBR to GPT format, you can use the steps below to create a bootable USB installation media to install Mac OS X.

Create USB install media

Use these steps to create a bootable media to install Mac OS X:

1. Download and install a copy of TransMac.

   Quick note: TransMac is a paid software, but it has a 15-day trial solution, that give us more than enough time to move the DMG files to the USB drive from Windows. (If you want to support the developer, you can purchase the full version.)

2. Insert the USB drive that you’ll use to fix your installation of OS X. (Remember that all the data in the USB will be erased. Make sure you take off any important documents.)

3. Right-click the TransMac software icon and Run as administrator. (You’ll be prompted to Enter Key or Run, because we’ll be using it once, click the Run option.)

4. On the left pane, you’ll see all the Windows PC drives listed, right-click the USB drive that you’re intending to use to reinstall Apple’s OS X and select the Restore with Disk Image option.

5. In the warning dialog box, click the Yes button.

6. Use the Restore Disk Image to Drive dialog box to browse for the DMG file with the installation files for Mac OS X Yosemite in this case, and click the OK button to create a bootable USB of the operating system.

   Now, you’ll have to wait a long time. No kidding. It could take one or two hours to complete the process depending on your computer and other variables.

Create Bootable Installer From Dmg

Once your bootable USB installation media is ready, remove it and insert it into your Mac, power it on, holding down the Option key, and select the USB you just created to reinstall Mac OS X.

If you’re having issues trying to create a bootable media, you can get a USB flash drive that comes with Mac OSX ready to install.

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.

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)

Create Mac Boot Usb From Dmg

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

Create Mac Bootable Usb From Dmg

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.

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.

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.