i prefer linux over windows, but sometimes need windows for access to device settings or the rare application that doesn't work in linux. this guide covers how i set up my computers to usually run linux but also give me an option to boot into windows instead.

partitions

each operating system needs its own section of disk, which is called a partition. with linux as the primary, i'm going to dedicate most of the space to that, with windows taking what's left.

make room for linux

i'm assuming you want to dual boot ubuntu and windows because you already have windows on your computer and want to try linux. that usually means your disk is set up for windows only, and you're going to need room to install linux separately (different partitions).

make sure you have enough disk space. it's hard to say how much that is, but you're not going to be able to install linux over the top of windows' files, so make sure the free space you have on windows is enough to get started on linux. you can uninstall programs you plan to use only on linux going forward, or use other ways to reclaim space. also make sure fast boot and bitlocker are off so the windows partition won't show locked / in use. leaving them this way also give you the option to mount your windows partition in linux.

download the latest ubuntu cinnamon desktop iso and the rufus usb utility. run rufus and use it to copy the iso to a usb drive. back up any essential information from windows because we're about to rearrange the disk. i haven't lost any data doing this, but if the power goes out in the middle or something else goes wrong it is possible. when you're ready, boot the ubuntu usb drive and choose try or install ubuntu.

it's not time to install yet -- we need to resize and (optionally) move the windows partition first. run gparted from the menu (easiest to find if you search it). it will probably select the disk with windows on it and show its partition(s) across the top. if not, you can find the disk in the upper right and switch to it. the largest partition is the one we're going to shrink and (optionally) move. select it and choose resize/move from the toolbar or context menu. i moved my windows partition down so the linux partition would be earlier on the disk by putting the size i wanted for the linux partition in the free space preceding box, leaving free space following at zero. you can save time by leaving windows where it is and making free space for linux following instead. after accepting this popup you need to actually apply the changes, which are going to take over an hour even with a fast nvme drive. once it's done you can reboot and windows should come up like nothing happened, except less total and free space on the C drive.

install ubuntu cinnamon

now you want the install ubuntu cinnamon icon from the desktop. choose your basic settings, which should mostly make sense to you. choose your keyboard layout and set up your internet connection. i like to choose the minimized installation so there isn't as much for me to remove. check both boxes for third-party software and support for media formats. the important part comes up next -- disk setup. you want the one to install ubuntu alongside windows. erasing the disk will lose your windows install and waste the partition work from earlier. you probably don't want manual or you wouldn't need a guide. i don't use encryption or advanced file system options. for my desktop i uncheck require my password to log in.