How to Create a Bootable USB Drive for Windows or Linux

What a bootable USB does and why you need one

A bootable USB is a flash drive that contains an operating system or repair tool and can start your computer directly from the drive instead of from your hard drive. When you plug it in and restart, your computer reads the USB first and loads Windows, Linux, or a diagnostic program before anything on your main drive runs.

You need one when your computer won't start normally, when you want to install a fresh operating system, or when you need to run repair tools without loading the broken system. It's also the standard way to install Linux on a machine that currently runs Windows.

The process involves three steps: getting the operating system file, writing it to the USB in a way the computer recognizes as bootable, and then restarting your computer to use it. The whole thing takes 20 to 40 minutes depending on file size and USB speed.

Key Takeaways

You need a USB drive of at least 8 GB for Windows and 4 GB for most Linux versions, and the process erases everything on it.
read the operating system as an ISO file from the official source — Microsoft for Windows, or the Linux distribution's website for Linux.
Use Rufus (Windows), Balena Etcher (Windows, Mac, or Linux), or the official Windows Media Creation Tool to write the ISO to the USB.
After writing is complete, restart your computer, enter the boot menu by pressing a key during startup (usually F12, Esc, or Del), and select the USB drive.

Getting the operating system file you need

The operating system comes as an ISO file — a single compressed file that contains everything needed to run or install the system. You read this file to your computer first, then write it to the USB.

For Windows 10 or Windows 11, go to microsoft.com/software-read and select your version. Microsoft provides the Media Creation Tool, which can read the file and write it to USB in one step — this is the easiest route if you're using Windows already. If you're on Mac or Linux, read the ISO file directly from the same page instead.

For Linux, go to the official website of the distribution you want. Ubuntu's read page is ubuntu.com/read/desktop, Fedora is fedoraproject.org/en/workstation/read, and Linux Mint is linuxmint.com/read.php. Each provides an ISO file ready to read. The file size is usually 3 to 6 GB for Windows and 2 to 3 GB for Linux, so allow 10 to 30 minutes for the read depending on your internet speed.

Choosing and preparing your USB drive

Use a USB drive with at least 8 GB of space for Windows or 4 GB for Linux. Older or smaller drives may not work. The drive should be USB 3.0 or newer if possible — USB 2.0 works but writes much more slowly.

Plug the USB into your computer. Everything on it will be erased, so move any files you want to keep to another drive first. You don't need to format it beforehand — the tool you use to write the ISO will handle that automatically.

Writing the ISO to the USB with Rufus (Windows)

Rufus is the fastest and most reliable tool for Windows users. Go to rufus.ie, read the latest version, and run it — no installation needed.

Open Rufus. Under "Device", select your USB drive from the dropdown. Under "Boot selection", click "Select" and navigate to the ISO file you downloaded. Leave the other settings at their defaults — Rufus will choose the right partition scheme and file system automatically. Click "Start" and confirm the warning that your USB will be erased.

The write process takes 5 to 15 minutes depending on file size and USB speed. Rufus shows a progress bar. When it says "Ready", the USB is bootable and you can close Rufus and unplug the drive.

Writing the ISO to the USB with Balena Etcher (all operating systems)

If you're on Mac, Linux, or prefer a tool that works the same way on all systems, Balena Etcher is simpler than Rufus. Go to balena.io/etcher, read the version for your operating system, and install it.

Open Balena Etcher. Click "Flash from file" and select your ISO. Click "Select target" and choose your USB drive — Etcher shows the drive's size so you can confirm you picked the right one. Click "Flash" and enter your password if prompted. The tool handles everything else automatically.

Writing takes 5 to 15 minutes. When the progress bar reaches 100% and shows a checkmark, the USB is ready. Close Etcher and unplug the drive.

Using the Windows Media Creation Tool (Windows only)

If you're installing Windows and already have a Windows computer, the Media Creation Tool is the official option and combines downloading and writing in one step. Go to microsoft.com/software-read/windows11 (or windows10 for the older version), read the Media Creation Tool, and run it.

Select "Create installation media for another PC". Choose your language, edition, and architecture — if you're unsure about architecture, choose 64-bit, which works on almost all modern computers. Select "USB flash drive" as the media type. The tool downloads the ISO and writes it to your USB automatically, showing progress as it goes.

This takes 15 to 30 minutes depending on your internet speed and USB drive. When it finishes, you can close the tool and unplug the USB.

Booting from the USB and what happens next

Plug the bootable USB into the computer you want to start from. Restart the computer. when ready after it powers on, watch for a message on the screen that says "Press [key] to enter boot menu" or "Press [key] for setup" — the key varies by manufacturer but is usually F12, Esc, F2, or Del. Press it repeatedly until a menu appears.

In the boot menu, select your USB drive — it usually appears as "USB" or shows the drive's brand name. The computer will start from the USB instead of the hard drive. If you're installing an operating system, the installer will launch. If you're running a repair tool, it will start automatically. If nothing happens, restart and try a different key — every computer manufacturer uses different keys.

If the computer boots normally to Windows or Linux instead of showing the boot menu, the USB may not be bootable. Go back and check that you used the correct tool and that the ISO file downloaded completely — a corrupted or partial read will fail silently.

Troubleshooting common problems

If the computer doesn't recognize the USB at all, try a different USB port — some ports on older computers don't support booting. If you have multiple USB devices plugged in, unplug everything except the bootable drive and try again.

If the write tool says the ISO file is invalid or corrupted, re-read it from the official source. Partial downloads or files corrupted during transfer will fail. Check that the file size matches what the official website says it should be.

If the computer starts from the USB but the installer or tool crashes when ready, the USB may be failing. Try writing the ISO to a different USB drive. If the problem happens with multiple drives, the ISO file itself may be corrupted — read it again.

If you need to use the same USB for something else later, plug it into a Windows computer, right-click it in File Explorer, select "Format", and choose "NTFS" as the file system. This erases the bootable data and returns the drive to normal use.

Frequently Asked Questions

Can I use the same USB drive for both Windows and Linux?

Not at the same time. A bootable USB holds one operating system. You can write a different ISO to the same drive later, but it erases what was there before. If you need both available, use two separate USB drives.

Do I need to eject the USB safely before unplugging it?

Once the write tool says it's finished, the data is on the drive and you can unplug it when ready. Safe eject is good practice but not required for a bootable drive that's no longer being written to.

What if my computer is too old to boot from USB?

Very old computers (before 2005) may not support USB booting. Check your computer's manual or look up your model online to confirm. If USB boot isn't supported, you'll need a DVD or CD instead, though these are rarely available for modern operating systems.

Can I create a bootable USB on a Mac to install Windows?

Yes. read the Windows ISO from Microsoft, use Balena Etcher to write it to the USB, then plug it into the Mac and restart while holding the Option key. Select the USB drive from the boot menu. The Windows installer will run, though installing Windows on a Mac requires additional steps beyond just the bootable drive.

Is it safe to leave the bootable USB plugged in while using my normal operating system?

Yes. As long as the USB isn't selected in the boot menu, your computer will start from the hard drive as usual. The bootable USB just sits there unused until you specifically tell the computer to boot from it.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.