How to Make a USB Bootable

Have an old USB drive lying around that you don't use anymore? Turn it into an operating install disk for Windows, Linux or Mac, or a diagnostic tool for your PC. Follow this guide to learn how.

Steps

Making a USB Drive to Install Any PC Operating System

Open the Command Prompt. You will need to run Command Prompt as an Administrator. Right-click on it and select Run as Administrator. You may need to enter the Administrator password.
- This method will create a USB drive that is bootable. You can then copy the contents of an operating installation disc onto the drive to create a portable installation drive.
- This method only works in Windows Vista, 7, and 8.

Open the disk management utility. This can be opened by entering the command diskpart.

Display the connected disks. Type the command list disk to show a list of all the drives connected to your computer. Your USB drive should be listed here as well. Make note of the number next to your USB drive.

Select the USB drive. Enter the command select disk #, replace “#” with the number from the previous step.

Clean the flash drive. Enter the command clean to have the disk management utility verify the integrity of the USB drive, and erase all data.

Create a bootable partition. Once the USB drive is clean, type in create partition primary. You will see a message saying that the operation was successful.

Select the new partition. Enter the command select partition 1 and press Enter. Once you receive a confirmation message, type active and press Enter. This will activate the partition.

Format the USB drive. Input the command format fs=fat32. When you press Enter, the program will work for a few minutes (if it is a small USB, e.g. 32Gb could actually take hours to SLOW format), and the progress will be displayed as a percentage.

Assign the USB a drive letter. Enter the command assign to give the thumb drive a letter designation. Type exit to end the disk management program.

Copy the operating system. Once the USB drive has been made bootable, you can copy over the installation files for the operating system you want to install. You can do this by dragging and dropping using your preferred file manager/explorer.
- Copy over any drivers you might need during the operating system installation to make the process much smoother.

Making a Windows Vista or 7 Install Drive

Create or Obtain A Windows Vista/7 ISO. Install a free burning program. There are a number of free burning utilities available online. You need one that can create ISO files. If you received your Windows 7 as a downloadable ISO file from Microsoft, you can skip to Step 2.
- Insert your Windows 7 DVD. Open your new burning program. Look for an option such as “Copy to Image” or “Create Image.” If prompted, select your DVD drive as the source.
- Save your ISO file. Choose an easy to remember name and location for the file. The ISO you make will be equal in size to the disc you are copying. This means it can take up several gigabytes of space on your hard drive. Be sure you have enough storage available.
- Creating the ISO can take a long time, depending on the speed of your computer and DVD drive.

Download Windows 7 USB/DVD Download Tool. This is available for free from Microsoft. Despite its name, this tool works with Windows Vista ISOs as well. You can run this tool on virtually any version of Windows.

Select the Source file. This is the ISO that you created or downloaded in the first section. Click Next.

Select USB device. You are given the option to either burn to a DVD or create a USB device. For this guide, click USB Device.

Choose your USB device. Make sure that your flash drive is connected correctly. You will need at least 4GB space on your flash drive to copy over the Windows installation.

Wait while program works. The program will format the USB drive to boot correctly, then copy the ISO file onto the drive. The copying process can take up to 15 minutes to complete, depending on the speed of your machine.

Making a Windows XP Install Drive

Gather your software and hardware. You will need USB_Prep8 and bootsect.exe. These are developer tools both freely available online. You will also need a flash drive at least 1GB in size, and a Windows XP installation CD or DVD.
- Insert the USB drive and the Windows XP disc. Close any Autoplay windows that open.

Extract and run USB_Prep8. Once you extract the USB_Prep8 .zip file, open the folder it creates and run usb_prep8.cmd. This will open a command prompt. Press any key to format the USB drive with PeToUSB. Note: In Windows 7, you will need to open a cmd as administrator and run usb_prop8.cmd from prompt, otherwise nothing works.

Start the format. Do not change any of the settings in the PeToUSB window. Once the format is complete, leave both windows open and start a new command prompt by pressing Windows key + R and typing “cmd” into the field.

Extract bootsect. Once it is extracted, navigate to the bootsect folder using the new command window. Once you are in the bootsect directory on your computer, type “bootsect.exe /nt52 Z:”. Change the “Z” to the drive letter of your USB drive.
- You cannot have any windows open showing the contents of the USB drive at this point, or the operation will fail and you will need to restart
- Bootsect copies the files necessary to allow your computer to boot from the flash drive. When it is complete you will see the message “Bootcode was successfully updated on all targeted volumes.” You can close this window and PeToUSB now, but keep the usb_prep8 command window open.

Adjust the Prep8 settings. Once the bootsect is done copying, the usb_prep8 command window will display a numbered menu allowing you to change some settings. You will need to change the first 3 settings:
- Press 1 and then Enter. A Browse for Folder window will open. Select the drive that contains your Windows XP disc and press OK.
- Press 2 and then Enter. If you have a drive on your computer that is already assigned to the letter T:, then change this option to a free letter. Otherwise, you can leave this as is.
- Press 3 and then Enter. Enter the drive letter for your USB flash drive.

Start the copy process. To do this, press 4 and then Enter. You will be notified that proceeding will format the virtual disk from the earlier menu. Press Y to continue. Once the format is complete, press any key to continue.
- Files will scroll up the screen as the copy process progresses. You will be prompted to press any key to continue again. After a few moments, a window will open confirming that you want to copy TempDrive Files. Press Yes, and wait around 15 minutes, then press Yes for the next two windows that open.

Begin Windows XP setup. At this point the USB drive is complete. Insert it into the computer that you want to install Windows XP on. You will need to set the BIOS to boot from a USB drive. Check out our guide on setting your BIOS correctly.
- When the startup menu opens, select Option 1 for a text mode installation. The Windows XP installation will now begin as normal.
- After the computer reboots after the text mode portion, select Option 2 to start the GUI (Graphical User Interface) portion of the installation.
- Keep your USB drive plugged in during the entire installation process.

Creating a USB PC Repair Toolkit

Download the Ultimate Boot CD (UBCD) ISO file. This file is available for free from the developers here. The UBCD is a collection of diagnostic tools that can be run before the operating system loads. Having them all on one thumbdrive makes for a convenient PC repair tool. You will also need the Universal USB Installer, which can be found here. Place the Universal USB Installer in the same folder as the UBCD .iso file.

Run the Universal USB Installer. Select Ultimate Boot CD from the menu. Make sure that the directory in the field is correct. Select the correct drive letter for your USB flash drive. Click the Create button.

Boot from the USB drive. After the USB is done being created, you’re ready to boot from the drive and run the diagnostic tool.

Making a Mac OS X 10.7 or 10.8 USB Install Drive

Assemble the hardware and software that you will need. You will need an 8GB or larger USB flash drive. You will also need the OS X installer app from the Mac App Store. Download the app and insert the USB drive.

Launch the Disk Utility. It can be found in the Utilities folder inside the Applications folder. The Disk Utility will allow you to manipulate the USB drive. In the left frame, select your USB drive and then open the Partition tab. Under Partition Layout, select 1 Partition.

Select the format. From the format dropdown menu, select Mac OS Extended (Journaled). This will allow your drive to be read by any Mac OS computer. Click the Options button and select GUID Partition Table.

Find the Install Mac OS X file. This is the .app file that you downloaded from the Mac App Store. It is installed in the Applications folder by default. Right-click on the file and select Show Package Contents. Open Contents and then Shared Support. You should see a file called InstallESD.dmg. Drag this file to your desktop.

Open the Disk Utility again. Click on the USB drive in the left frame. Open the Restore tab and click the Image… button next to the Source box. Select the InstallESD.dmg file. For Destination, drag the newly created partition into the field.

Click the Restore button. You will be asked for confirmation before the copy process begins. Press Erase to continue. The process can take up to an hour to complete, depending on the speed of your Mac. Once it is finished, you can boot from the USB drive and install Mac OS X as if you were using a disc.