How to Create a Bootable Ubuntu USB Drive on Windows, Mac, or Linux

What you need before you start

A bootable Ubuntu USB drive lets you run Ubuntu directly from the USB stick without installing it, or use it to install Ubuntu on a computer. You will need three things: a USB drive with at least 4 GB of storage space (8 GB is safer), a computer with Ubuntu already downloaded as an ISO file, and software to write that ISO file onto the USB drive.

The USB drive does not need to be empty — the process will overwrite whatever is on it, so back up any files you want to keep first. The ISO file is a single large file that contains the entire Ubuntu operating system. You can download it free from ubuntu.com/download/desktop.

The steps differ depending on whether you are using Windows, Mac, or Linux. Each section below covers one operating system. You only need to follow the section for the system you are using right now.

Key Takeaways

Download the Ubuntu ISO file from ubuntu.com/download/desktop, then use Balena Etcher (works on Windows, Mac, and Linux) or your operating system's built-in tool to write it to a USB drive.
Windows users can use Rufus or Balena Etcher; Mac users should use Balena Etcher or the command line; Linux users can use GNOME Disks or the dd command.
The process erases everything on the USB drive, so move any files you need to a different location first.
After writing the ISO, restart your computer and boot from the USB drive by pressing a key during startup — usually F12, Esc, or Del, depending on your computer model.

Creating a bootable USB on Windows

The easiest tool for Windows is Balena Etcher, which works the same way on all three operating systems. Download it from balena.io/etcher, install it, and run it. Click "Flash from file", select the Ubuntu ISO file you downloaded, then click "Select target" and choose your USB drive from the list. Click "Flash" and wait — it usually takes 5 to 15 minutes depending on your USB drive speed.

If you prefer not to install extra software, Rufus is another option that does not require installation. Download it from rufus.ie, run the executable file, select your USB drive, click the disk icon next to "Boot selection", choose your Ubuntu ISO file, and click "Start". Rufus will warn you that it will erase the drive — click "OK" to continue.

Do not use Windows File Explorer to copy the ISO file onto the USB drive. That will not create a bootable drive — it will just copy a file. The ISO file must be written to the drive at the sector level, which is what Balena Etcher and Rufus do.

Creating a bootable USB on Mac

Balena Etcher is the simplest option on Mac as well. Download it from balena.io/etcher, open the DMG file, drag Balena Etcher into your Applications folder, then open it from Applications. Click "Flash from file", select your Ubuntu ISO, click "Select target", choose your USB drive, and click "Flash".

If you want to use the command line instead, insert the USB drive, open Terminal, and type diskutil list to see all connected drives. Find your USB drive in the list — it will show a size that matches your drive. Note the identifier, which looks like disk2 or disk3. Then type diskutil unmountDisk /dev/diskX (replace X with your disk number), then sudo dd if=/path/to/ubuntu.iso of=/dev/rdiskX bs=4m (replace the path with your actual ISO file location and X with your disk number). This takes several minutes and shows no progress — wait until you see the command prompt again.

Mac will show a warning that the USB drive is not readable when you insert it after writing the ISO. This is normal — the drive is bootable, not a regular Mac drive. Click "Eject" and the drive is ready to use.

Creating a bootable USB on Linux

On Ubuntu or other Linux systems, GNOME Disks is built in and handles this task directly. Insert the USB drive, open GNOME Disks (search for "Disks" in your applications menu), select your USB drive from the list on the left, click the menu button (three horizontal lines) at the top right, and select "Restore Disk Image". Choose your Ubuntu ISO file and click "Start Restoring". The process takes a few minutes.

From the command line, insert the USB drive and type lsblk to list all drives. Find your USB drive — it will show a size matching your drive. Note the device name, which looks like /dev/sdb or /dev/sdc. Unmount it by typing sudo umount /dev/sdX* (replace X with your drive letter). Then type sudo dd if=/path/to/ubuntu.iso of=/dev/sdX bs=4M status=progress (replace the path with your ISO location and X with your drive letter). This command shows progress as it writes. When it finishes, type sync to ensure all data is written, then you can eject the drive.

Never use the partition name (like /dev/sdb1) with dd — always use the device name without a number (like /dev/sdb). Using the wrong device can erase your main hard drive.

Booting from the USB drive

Insert the USB drive into the computer where you want to run or install Ubuntu. Restart the computer and watch the screen carefully during startup. Most computers show a message like "Press F12 to enter boot menu" or "Press Esc for startup options" — the key varies by manufacturer. Press that key repeatedly as the computer starts up, before the operating system loads.

A menu will appear showing available boot devices. Select your USB drive from the list — it will be labeled with the USB drive name or manufacturer. The computer will boot from the USB drive and Ubuntu will start. This takes longer than a normal startup because it is running from a USB drive rather than a hard drive.

If you do not see a boot menu, restart again and try a different key. Common keys are F2, F10, F12, Del, and Esc. If you are unsure, search online for your computer model and "boot menu key" — manufacturers publish this information.

Troubleshooting common problems

If the USB drive does not boot, the ISO file may not have been written correctly. Repeat the process with Balena Etcher, which is the most reliable tool across all three operating systems. Make sure you selected the USB drive as the target, not a partition on your main hard drive.

If the computer boots into the old operating system instead of the USB drive, the USB drive may not be set as the first boot device. Restart and enter the boot menu again — this time look for a boot order or boot priority option. Move the USB drive to the top of the list and save the changes.

If you see an error about a missing or corrupted file after Ubuntu starts, the ISO file itself may be corrupted. Download it again from ubuntu.com/download/desktop and verify the file by checking its SHA256 checksum against the value listed on the download page. Instructions for checking the checksum are on the same page.

What to do after Ubuntu boots

When Ubuntu starts from the USB drive, you will see a desktop with an "Install Ubuntu" icon. You can click this to install Ubuntu on the computer's hard drive, or you can explore Ubuntu without installing it by closing the installer window. Running Ubuntu from the USB drive is slower than an installed version because everything loads from the USB drive, but it lets you test Ubuntu before committing to an installation.

If you want to keep the USB drive bootable for future use, do not write over it with other files. You can use it to boot any computer that supports USB booting. To use the USB drive for regular file storage again, you will need to format it as a regular drive using your operating system's disk utility.

Frequently Asked Questions

Can I create a bootable USB on a Mac and use it on a Windows computer?

Yes. The Ubuntu ISO file is the same regardless of which operating system you use to write it to the USB drive. A bootable USB created on a Mac will boot on Windows, Linux, or any other computer that supports USB booting.

What if my USB drive is smaller than 4 GB?

Ubuntu requires at least 2 GB to run from USB, but 4 GB is recommended because some versions are larger. If your drive is between 2 and 4 GB, try writing the ISO anyway — it may work. If it fails, you will need a larger drive.

Do I need to format the USB drive before writing the ISO?

No. The ISO writing process erases and formats the drive automatically. Formatting it first does not help and wastes time.

Can I use the same USB drive to boot multiple different Linux distributions?

Not at the same time. Writing a new ISO file to the USB drive erases the previous one. You would need a separate USB drive for each distribution, or use a tool like Ventoy that lets you store multiple ISO files on one drive.

Why does the Ubuntu boot take so long the first time?

Ubuntu is loading the entire operating system from the USB drive into memory, which is much slower than loading from a hard drive. This is normal. Once Ubuntu is fully loaded, it runs at normal speed. An installed version on a hard drive will start much faster.

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