How to Create a macOS Bootable USB on Windows 11 (TransMac + DiskPart)

If your Mac refuses to start and your only working computer is a Windows 11 PC, you can still create a macOS bootable USB drive and recover your Mac. This process is more involved than creating a Windows 11 bootable USB because Apple does not provide an official Windows tool for macOS installer media. Instead, you use a third-party utility called TransMac, along with Windows’ built-in DiskPart tool when needed.

This guide covers the full process: requirements, formatting, writing the macOS image, booting the Mac from the USB, and fixing the most common problems when the USB does not show up.

What You Need Before You Start

Gather everything below before opening any tool. Missing any one item will stop the process partway through.

Only use macOS DMG files from Apple’s official source. Files from unknown third-party websites may be modified, incomplete, or carry malware.

Method 1: Create a macOS Bootable USB Using TransMac

TransMac is a Windows utility that reads and writes Mac-formatted drives. It handles both the Mac-compatible format step and the disk image write in a single workflow.

Step 1: Download and Install TransMac

Download TransMac from the official Acuate Systems website (acutesystems.com/scrtm.htm). Install it on your Windows 11 PC using the default settings.

After installation, right-click the TransMac shortcut and select Run as administrator. TransMac requires low-level drive access to format and write the USB drive, so running it without administrator rights will cause it to fail.

TransMac offers a 15-day free trial. No purchase is needed to complete this process.

Step 2: Insert the USB Drive and Format It for Mac

Connect your 32GB or larger USB drive to the PC. Back up anything on it first because this step erases all existing data.

In TransMac:

1. Right-click your USB drive in the left sidebar.
2. Select Format Disk for Mac.
3. Enter a name for the drive, such as “macOS Bootable USB.”
4. Click OK and confirm the warning.
5. Wait for the format to complete.

Windows-formatted USB drives typically use the MBR partition scheme. TransMac converts the drive to GPT during this step. GPT is required for most Macs to recognize external boot media.

Step 3: Restore the macOS DMG to the USB

After the format completes:

1. Right-click the USB drive again in the left sidebar.
2. Select Restore with Disk Image.
3. Click the browse button and select your macOS .dmg file.
4. Click OK and confirm the warning.
5. Wait for the write process to finish.

A modern macOS installer is typically 12 to 15GB. On a USB 2.0 drive, expect 30 to 60 minutes. On a USB 3.0 drive, the process usually takes 15 to 25 minutes. Do not interrupt it.

Step 4: Safely Eject the USB

Once TransMac finishes, use Windows to safely eject the USB drive before unplugging it. Pulling the drive out while the system is still writing data can corrupt the installer and force you to repeat the entire process.

Troubleshooting: TransMac Does Not Recognize the USB Drive

If TransMac does not recognize your USB drive, or if the Mac boot menu does not show the USB after writing, the drive may still carry a Windows-style partition layout that TransMac cannot overwrite cleanly. You can fix this by preparing the USB with DiskPart first.

Warning: DiskPart erases the selected disk completely. Confirm the disk number carefully before running any command. Selecting the wrong disk number can erase your Windows drive or another storage device.

1. Open Start, search for Command Prompt, right-click it, and select Run as administrator.
2. Type diskpart and press Enter.
3. Type list disk and press Enter to view all connected drives.
4. Identify your USB drive by its size.
5. Type select disk X and press Enter, replacing X with the correct disk number for your USB drive.
6. Type clean and press Enter.
7. Type convert gpt and press Enter.
8. Type create partition primary and press Enter.
9. Type exit and press Enter.

After this, return to TransMac. Right-click the USB drive, choose Restore with Disk Image, select your macOS .dmg file, and complete the restore. If TransMac still prompts you to format the drive for Mac before restoring, allow it to continue before writing the image.

How to Boot Your Mac from the USB

After the USB is ready, plug it into the Mac and follow the steps for your Mac type.

On Apple Silicon Macs (M1, M2, M3, M4)

1. Shut down the Mac.
2. Connect the USB installer directly to the Mac.
3. Press and hold the power button.
4. Keep holding until the startup options screen appears.
5. Select the bootable USB installer.
6. Click Continue.

Apple Silicon Macs use the power button hold method to access startup options. The Option key shortcut used on Intel Macs does not apply here.

On Intel Macs

1. Shut down the Mac.
2. Connect the USB installer.
3. Turn on the Mac.
4. Immediately hold the Option (Alt) key.
5. Select the USB installer from the Startup Manager screen.
6. Press Return.

What to Do If the USB Does Not Show Up

Use this table to match your problem to the correct fix:

Intel Macs with the Apple T2 Security Chip block external boot by default. To allow it, you need to boot into macOS Recovery on that machine, open Startup Security Utility, and set the external boot option to allow. If the Mac cannot boot at all, you may need another Mac to adjust that setting first.

If You Have Access to Another Mac, Use Apple’s Official Method

If you can borrow any compatible Mac, use Apple’s official createinstallmedia Terminal command instead. Apple’s method downloads the full verified macOS installer directly from Apple, formats the USB automatically, and is far more reliable than the Windows method.

The command format looks like this:

sudo /Applications/Install\ macOS\ Sonoma.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

Replace Sonoma with the macOS version name you downloaded. The USB drive gets erased automatically and formatted as Mac OS Extended during the process.

For the best chance of success, follow this order:

1. Try macOS Recovery on the Mac first.
2. If Recovery fails, create the installer on another Mac using Apple’s official command.
3. If only a Windows 11 PC is available, use TransMac with a trusted macOS DMG file.
4. For unsupported older Macs, use OpenCore Legacy Patcher instead of TransMac.

The Windows method works, but success depends on the macOS image, the USB drive, the Mac model, and the Mac’s boot security settings. Using a clean USB drive and a verified DMG file eliminates most failure points.

Related Tech Guides

• How to Create a Windows 11 Bootable USB
• How to Create a WinPE Bootable Disk for Windows 11
• How to Format a FAT32 Drive Larger Than 32GB in Windows 11