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This guide will show you how to convert a standard USB drive into a bootable device for installing or setting up an operating system on your computer. This method is especially useful when you need to install an OS (such as Windows) on a computer without a CD/DVD drive. You can create a bootable USB on either a Windows or Mac computer using free tools like Command Prompt or Terminal. For the latest versions of Windows 10 or 7, you can use the Windows 10 or 7 installation tool to format the USB. Note that a USB is not required for installing the latest version of Mac OS.
Steps
Using Command Prompt on Windows
Insert the USB into your computer. Plug the USB into one of the rectangular USB ports on your computer. USB drives can only be inserted one way, so avoid using excessive force if it doesn’t fit.
- The USB must have at least 8GB of free space to accommodate the operating system installation files.
Type command prompt to search for the Command Prompt program on your computer.
- If your computer mouse doesn’t have a right-click button, click the right side of the mouse or use a two-finger tap.
- If your computer uses a trackpad instead of a traditional mouse, use two fingers to tap the trackpad or press the bottom-right corner.
Click on Run as administrator in the options list.
Click Yes when prompted to confirm and open Command Prompt.
Enter the "partition" command. Type diskpart and then press Enter to proceed.
- You will be asked to confirm this action before continuing.
Display the list of connected drives. Type list disk into Command Prompt, then press ↵ Enter.
Locate your USB drive. Identify the correct drive by checking its name, label, or storage capacity in GB.
- If you can’t recognize your USB drive, disconnect it, run the "disk list" command, reconnect the USB, run "disk list" again, and check which drive wasn’t listed the first time.
- The USB drive is usually at the bottom of the menu.
Select the USB drive. Type select disk number into Command Prompt, replacing "number" with the USB drive’s position in the list, and press ↵ Enter.
Erase all contents on the USB drive. Type clean and then press ↵ Enter.
Create a new partition on the USB drive as follows:
- Type create partition primary and press ↵ Enter.
- Type select partition 1 and press ↵ Enter.
- Type active and press ↵ Enter.
Format the USB drive. Type format fs=fat32 quick into Command Prompt, then press ↵ Enter.
- If you encounter errors during the process, repeat it using the command format fs=ntfs quick.
Assign a drive letter to the USB. Type assign and press ↵ Enter. A confirmation message will appear in the Command Prompt window.
Close the Command Prompt window. You now have a bootable USB, meaning you can save an operating system ISO file or a computer hard drive backup to the USB for installation on another machine.
Using Terminal on Mac
Insert the USB into your computer. Plug the USB into one of the rectangular or oval USB or USB-C ports on your computer. Standard USB drives can only be inserted one way, so avoid using excessive force if it doesn’t fit.
- If your Mac uses USB-C ports, the USB will fit into the USB-C port regardless of orientation.
- The USB must have at least 8GB of free space to accommodate the operating system installation files.
Ensure you have the ISO file. To create a bootable USB on a Mac, you need an ISO file (or a backup copy if you’re cloning your computer’s hard drive) ready to drag and drop into Terminal.
- This step differs from how Windows handles bootable USBs, as Windows allows you to create and save a bootable USB for later use.
Type terminal to search for the Terminal application on your Mac.
Display the list of connected drives. Type diskutil list into Terminal, then press ⏎ Return.
Locate the USB drive. Find the USB drive you’ve connected to your computer, then identify its name under the "IDENTIFIER" heading. The USB drive is usually listed under the "(external, physical)" heading near the bottom of the Terminal window.
- The USB drive name under "IDENTIFIER" is typically "disk1" or "disk2".
Select the USB drive. Type diskutil unmountDisk /dev/disknumber—remember to replace "disknumber" with the name and number (e.g., disk2) of the drive under the "IDENTIFIER" heading in Terminal, then press ⏎ Return.
Enter the formatting command. Type sudo dd if= but do not press ⏎ Return.
Drag the ISO file into the Terminal window. Click and drag the ISO file (or disk copy) you want to use for the USB installation into the Terminal window. This action will save the file’s path into the Terminal command.
- You can also manually type the file path to the ISO.
Press the Space key. This adds a space at the end of the file path to create room for the next part of the command.
Enter the remaining part of the command. Type of=/dev/disknumber bs=1m, replacing "disknumber" with the USB drive’s identifier (e.g., disk2), then press ⏎ Return.
Enter your password. This is the password you use to log into your Mac. While typing, you won’t see the characters displayed in Terminal; this is normal.
Press ⏎ Return. This confirms your password and instructs the computer to begin creating the bootable USB with the selected ISO or disk image file.
- This process may take several hours, so keep Terminal open and ensure your Mac is charging.
Using the Windows 10 Installation Tool
Know when to use this method. The Windows 10 Installation Tool is a program that transfers Windows 10 installation files to a USB and creates a bootable USB. This method is only useful when using Windows to create a Windows 10 installation USB.
Open the Windows 10 installation page. This page contains the tool you’ll use to create the bootable USB.
Insert the USB into your computer. Plug the USB into one of the rectangular USB ports on your computer. USB drives can only be inserted one way, so avoid using excessive force if it doesn’t fit.
- Your USB must have at least 8GB of free space.
Click the blue Download tool now button in the middle of the page. This will download the installation file to your computer.
Open the installation tool. Double-click the downloaded installation tool file, then select Yes when prompted.
- The installation tool will be saved in your browser’s default "Downloads" folder (or on your desktop).
Click Accept at the bottom of the installation tool window.
Check the box labeled "Create installation media" in the middle of the window.
Click Next in the bottom-right corner of the window.
Click Next once more. This will set your computer’s properties as the default configuration for the installation files.
- If you want to choose a different language, version, or architecture (e.g., 32-bit) instead of using the default settings, uncheck the box labeled "Use the recommended options for this PC" and adjust the settings before clicking Next.
Check the box labeled "USB flash drive" in the middle of the window.
Click Next.
Select a drive. Click on the name of the drive you want to use.
Click Next at the bottom of the window. This begins formatting your USB drive for Windows 10 installation—a process that includes erasing existing files, creating a bootable USB, and adding the Windows 10 ISO files.
Using the Windows 7 Installation Tool
Insert the USB into your computer. Plug the USB into one of the rectangular USB ports on your computer. USB drives can only be inserted one way, so avoid using excessive force if it doesn’t fit.
- The USB must have at least 4GB of free space.
Download the Windows 7 ISO file as follows:
- Visit the Windows 7 download page.
- Enter your Windows 7 product key.
- Select Verify.
- Choose your language.
- Click Confirm.
- Select the Download option: 32-bit or 64-bit.
Open the Windows USB/DVD Download Tool page. This page contains the tool that allows you to create a bootable USB and save the Windows 7 installation files to it.
Click the orange Download button in the middle of the page.
Select a language. Click the box to the left of the version of the tool you want to use. For example, if you want the English (US) version, look for the line with "US" near the end of the version name.
Click the blue Next button in the bottom-right corner of the page. This will initiate the download of the tool to your computer.
Install the Windows 7 USB/DVD Download Tool. Double-click the downloaded installation file, then follow the on-screen instructions.
Open the program. Double-click the "Windows 7 USB DVD Download Tool" program icon on your computer’s desktop to open a new window.
- When prompted, click Yes to proceed.
Select the Windows 7 ISO file. Click Browse, then choose the ISO file you downloaded earlier and click Open.
Click Next at the bottom of the window.
Click the USB device button in the bottom-right corner of the window.
Select your USB drive. Click on the name of the USB drive you want to use.
Click the Begin copying button in the bottom-right corner of the window. This initiates the creation of a bootable USB and copies the Windows 7 installation files to the USB.
Tips
- Using Command Prompt or Terminal allows you to create a bootable USB for installing Linux operating systems.
Warnings
- Formatting a USB will erase all its contents. If the USB contains important data, make sure to back it up before creating a bootable drive.
