How to Create a Bootable Ubuntu USB in Windows

We know there are a lot of people who swear by Ubuntu, but there are also Windows users who just want to dabble in the open-source platform. If you’re one of the latter, then it could be handy to have a bootable Ubuntu USB so that you can run the OS without committing to a full install. It can also help if you want to use the relatively secure Ubuntu on public computers in faraway places, booting it up with all your essential software on the go.

If that’s what you’re after, this guide will show you how to create a bootable Ubuntu USB in Windows.

First, you’ll need to download the latest version of Ubuntu from the official Ubuntu website. (Get the default 32-bit version because that will run on a wider range of machines.)

Unless you have super-fast Internet while that’s happening (it’s a 1.4GB download from a fairly slow server), you can download the tool we’re going to use to create the bootable USB. It’s the tried and tested UNetbootin, and you can download it here.

With UNetbootin and the Ubuntu ISO file downloaded, it’s time to join the two together.

Open UNetbootin and select “Diskimage.” From the dropdown next to it, select ISO, then click the three-dotted icon to load the Ubuntu ISO that you downloaded to your hard drive earlier.

Here you can select the “Distribution” option instead, which will download Ubuntu (or whichever Linux version you want) automatically, but last I checked this list didn’t have the 32-bit version of the latest Ubuntu, so getting the ISO directly works better in this case. Still, it’s good to know.


Underneath that, you can pick how much space you want to preserve across reboots. (It’s known as “persistence” and allows you to save your files, settings and so on.) Don’t touch this because it has a tendency not to work. (We’ll show you how to make your Ubuntu USB persistent shortly.)

In the “Type” dropdown at the bottom, make sure “USB Drive” is selected, select the Drive directory of your USB drive next to it, then click “OK” to start the process. After several minutes, the process will be complete.

You now have a bootable, portable Ubuntu build.

Before you run it, you’ll need to create a “casper-rw” file, which is what allows your portable version of Ubuntu to save files and keep them. To do this, you’ll need to download a tool called PDL Casper-RW Creator for Windows, which is the fastest, easiest way to create a functioning persistence file.


Using the tool is simple – just select the drive where your USB flash drive is plugged in, then drag the slider up to a maximum of 4090MB, which represents the amount of storage space you can dedicate to your persistence file. Obviously, this will be subject to how much space you have on your USB flash drive after you’ve installed Ubuntu on it.

Next, you’ll need to go to the “boot/grub” directory on your newly created USB Ubuntu drive and open the “grub.cfg” file. Here, look for the line that says:

linux /casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash

After the word “splash,” leave a space and write “persistent,” then save the config file.


Reboot your PC, then repeatedly press the key to go into your BIOS. (This varies, but in my case it’s F2 or Delete.)

Make sure that the Ubuntu USB drive is first in the load order which will ensure that whenever it’s inserted, your PC will boot to Ubuntu rather than Windows or other operating systems. (The USB drive should be top of the load order by default, but on my PC I still had to go into the BIOS then Exit, just to remind it – it’s a quirk that happens on quite a few PCs.)

On the Ubuntu menu,  pick “Try Ubuntu without installing” to get it running.


You now have a portable Ubuntu drive that you can take anywhere with you. It’s a great option in the way of security, ensuring that you don’t have to go entering and leaving your data on strangers’ or public computers. As an extra measure, though, remember to password-protect your Ubuntu drive.

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