What you need to create a bootable USB stick

A bootable USB stick is a flash drive that contains an operating system or repair tool and can start your computer directly from the USB port instead of from your hard drive. To make one, you need three things: a USB stick (at least 4 GB for most operating systems, 8 GB or larger for Windows), a computer that already works, and free software that writes the operating system image to the USB stick.

The process differs slightly depending on whether you're using Windows, macOS, or Linux on your working computer, and which operating system you want to install. The most common scenarios are installing Windows 10 or 11, installing Linux distributions like Ubuntu, or creating a repair disk for troubleshooting.

Your USB stick will be erased during this process, so move any files you want to keep to another location first. The stick itself doesn't need to be new — any USB drive will work as long as it has enough space.

Key Takeaways

  • Download the operating system image file (usually an .iso file) from the official source — Microsoft for Windows, Canonical for Ubuntu, or the relevant Linux project.
  • Use free software like Rufus (Windows), Balena Etcher (Windows, macOS, Linux), or GNOME Disks (Linux) to write the image to your USB stick.
  • The USB stick will be completely erased, so back up any files on it before you start.
  • After writing is complete, restart your computer and change the boot order in BIOS or UEFI to boot from USB first, or use the boot menu key during startup.

Getting the operating system image file

Before you can create a bootable USB stick, you need the operating system itself as an image file, usually named with an .iso extension. Download this file from the official source only — downloading from third-party sites risks getting a corrupted or modified file.

For Windows 10 or 11, go to microsoft.com/software-download and select the version you need. Microsoft provides a download tool that guides you through the process. For Ubuntu Linux, visit ubuntu.com/download/desktop and download the latest long-term support (LTS) version unless you have a specific reason to use a newer release. For other Linux distributions, find the official download page for that project — for example, fedoraproject.org for Fedora or debian.org for Debian.

The download may take 10 to 30 minutes depending on your internet speed and which operating system you're downloading. The file size is typically 4 to 6 GB for Windows and 2 to 3 GB for most Linux distributions. Once the download finishes, note where the file is saved — usually your Downloads folder.

Creating a bootable USB stick on Windows

Rufus is the most straightforward tool for Windows users. Download it from rufus.ie (it's free and requires no installation). Plug in your USB stick, open Rufus, and it will automatically detect the drive. Click the disk icon next to "Boot selection" and navigate to the .iso file you downloaded. Leave the other settings at their defaults unless you have a specific reason to change them.

Click "Start" and Rufus will warn you that the USB stick will be erased — this is normal and expected. Click "OK" to proceed. The writing process usually takes 5 to 15 minutes. When it finishes, you can close Rufus and remove the USB stick.

If you prefer not to download additional software, Windows 11 users can use the built-in Windows Backup tool, though it only works for creating Windows installation media. For other operating systems or if you want a more universal tool, Balena Etcher (balena.io/etcher) works on Windows, macOS, and Linux and handles any .iso file.

Creating a bootable USB stick on macOS

macOS users should download Balena Etcher from balena.io/etcher. It's free, works with any operating system image, and has a simple three-step interface. Download and install it, then open the application.

Click "Flash from file" and select the .iso file you downloaded. Click "Select target" and choose your USB stick from the list — be careful here, as selecting the wrong drive will erase it. Click "Flash" and enter your Mac password when prompted. The process takes 5 to 15 minutes depending on the file size and your USB stick's speed.

Alternatively, advanced macOS users can use the command line with dd or ddrescue, but Balena Etcher is simpler and less error-prone for most people.

Creating a bootable USB stick on Linux

Linux users have several options. GNOME Disks is built into most distributions and works well. Open Disks, select your USB stick from the left sidebar, click the menu button (three horizontal lines), and select "Restore Disk Image". Navigate to your .iso file and click "Start Restoring". Enter your password when prompted.

Balena Etcher also works on Linux and may be easier if your distribution doesn't include GNOME Disks. Download it from balena.io/etcher, install it using your distribution's package manager or the provided installer, and follow the same steps as on macOS.

Command-line users can write the image directly using dd: first identify your USB stick with lsblk, then run sudo dd if=/path/to/image.iso of=/dev/sdX bs=4M status=progress, replacing sdX with your actual device (for example, sdb). Be extremely careful with this command — using the wrong device name will erase the wrong drive.

Booting from the USB stick

Once the USB stick is created, plug it into the computer where you want to install or repair the operating system. Restart that computer and watch for a message during startup that says something like "Press F12 to enter boot menu" or "Press Del to enter Setup". The exact key varies by manufacturer — common ones are F2, F10, F12, Del, and Esc.

If you see a boot menu, select your USB stick from the list (it may be labeled as "USB Device" or by the stick's brand name). If you don't see a boot menu, restart again and enter the BIOS or UEFI settings instead (usually Del or F2), find the boot order section, and move the USB drive to the top of the list. Save and exit, and the computer will restart and boot from the USB stick.

If the computer doesn't recognize the USB stick at all, try a different USB port — some ports may not support booting. If you're still having trouble, restart the computer and try again, watching more carefully for the boot menu prompt.

Troubleshooting common problems

If the USB stick doesn't boot, the most common cause is that the image wasn't written correctly. Plug the stick into your working computer, delete all files on it, and run the writing tool again. Make sure you're using the official .iso file from the correct source — corrupted or incomplete downloads are a frequent problem.

If the computer won't recognize the USB stick during startup, try a different USB port, preferably one on the back of the computer if it's a desktop. Some computers have USB 3 ports that don't support booting — try a USB 2 port instead (usually black instead of blue). If you're creating a Windows installation stick on a Mac or Linux computer, make sure you're using the Windows .iso file, not the Mac or Linux version.

If you see an error message during the installation process after booting from the USB stick, the problem is usually with the installation itself rather than the bootable stick. Restart the computer, boot from the USB stick again, and try the installation once more.

Frequently Asked Questions

Can I use the same USB stick to install different operating systems?

Yes, but you'll need to erase it and write a new image each time. The writing process completely replaces the previous contents, so you can't have multiple operating systems on one stick simultaneously. If you want to keep multiple installation media, use separate USB sticks.

Do I need to format the USB stick before writing the image?

No. The writing tools like Rufus and Balena Etcher handle formatting automatically as part of the process. Formatting the stick beforehand won't help and isn't necessary.

What if my computer doesn't have a USB port?

Older computers may only have USB 2 ports or no USB at all. You can use a USB hub or adapter, though booting from a hub is less reliable than booting from a direct port. For very old computers, you may need to use a CD or DVD instead — check your computer's manual for supported boot media.

Can I use a USB stick that already has files on it?

Yes, but all files on it will be erased when you write the operating system image. Move any files you want to keep to another location first, then proceed with creating the bootable stick.

How long does it take to write the image to the USB stick?

Most images take 5 to 15 minutes to write, depending on the file size and the speed of your USB stick and computer. USB 3 sticks are faster than USB 2, but even USB 2 is usually fast enough. The progress bar in your writing tool will show you how much time remains.