Create Mac Dmg On Windows
If your Mac suddenly refuses to boot up properly, you might need bootable macOS install USB 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.
You will need to give admin privileges to the software. Alternatively, you can run the program as admin when you launch it.Step 4: Select the USB drive in the section called Destination USB Drive.Step 5: Leave all other default as they are and click on 'Start' to.You should be able to see the progress, and a new popup will appear when the bootable media is ready. 
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. Os x 10.12 dmg. 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.
Part 2: Format USB Drive to GPT
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
Create Mac Dmg On Windows 7
Create macOS Sierra Bootable USB Installer on Windows 10. To create a Bootable USB Installer, you need to download macOS Sierra image file from the link below and other data that mentioned in the download section with an 8 or higher USB flash drive. Create macOS High Sierra Bootable USB Installer on Windows 10 Firstly, you need to download macOS High Sierra DMG file from the link below. Also, with the DMG your should the download the TransMac software from the link down below, and for the flash drive, you need 8 GB or higher.
You have now formatted the partition of USB drive. It's time to download TransMac for Windows. Although this is a premium software, you can use the initial free trial period to create a bootable macOS USB drive on Windows 10. After installing the application, follow the sequence of steps shown below:
Step 1: Right-click the icon and select Run as Administrator from the contextual menu. Choose Run when prompted.
Step 2: Insert your formatted USB drive, and you will be able to see it in the TransMac software on the left panel.
Step 3: Right-click the USB and select Restore with Disk Image in the contextual menu. Click Yes in the warning popup.
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Step 4: You will see a window that says Restore Disk Image to Drive. Here, select your DMG file in the dropdown menu and click OK.
Depending on the system configuration, this can take anywhere from a few minutes to a couple of hours. Once the progress bar is at 100%, a bootable USB is ready.
Part 4: Boot macOS Install USB on Mac
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.
Create Bootable Usb From Dmg Mac On Windows
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 TransMac software won't be bootable, which means you can't install macOS using it, and you may need to do the whole thing over again.