When I buy a PC, it almost always comes with Win 10 these days and I am not brave enough to throw it away. So I install Linux beside Windows. For this I need to shrink the Windows partition. Windows is unwilling to shrink its NTFS partition to less than half its original size. That's because it has placed the Master File Table in the middle of the partition and considers it unmovable. There are third party tools that can do this but I don't want to learn about them or trust them. So use Linux to resize the partition to give Windows less than half of the disk. There are a couple of tricks that you need to know. Windows 10, by default, uses something called Fast Startup. That means that when you ask it to shut down, it only hibernates. I think that that means that if you change its partition (or any of several other things) while it is shut down, Bad Things might happen. I think that it is best turn off Fast Startup before shutting down Win 10. Settings: System: Power and Sleep: Additional Power Settings: Choose what the power buttons do: Change settings that are currently unavailable: Under Shutdown Settings, untick: Turn on fast startup (recommended) (I don't think that Microsoft wants you to find this.) Shutdown Windows 10. Boot your favourite Live linux (need not be what you install). Run gparted to resize the NTFS partition. SUPERSTITIOUS MODE ON /* this seems to be needed */ Immediately shut down Linux. Reboot Windows (it will repair some damage caused by ntfsresize). Shut down Windows. SUPERSTITIOUS MODE OFF Install Linux however you wish to. You can turn on Windows' fast startup. But only if Linux and Windows share no filesystems. ================ Alternative solution (unreliable report of Giles' approach): Before EVER booting Wind 10, install Linux. Win 10 first-boot process won't eat a Linux installation.