How do I extend C drive in Windows 10 PC without formatting?

Windows' Disk Management can be pretty limited. For instance, you can only extend the C drive if there's unallocated space directly next to it. If your D drive (or any drive) is in between, you won't be able to extend C without some extra steps, like using third-party software.

If you're trying to extend C drive in Windows 10 without formatting, and you're changing other partitions, be careful. Sometimes, the setup can get confused, especially if you're shrinking a partition. Always ensure that the right partition is set as active. Before modifying partitions, run a disk check to ensure there are no file system errors. You can do this by opening Command Prompt (as admin) and typing chkdsk /f. Addressing any errors ahead of time can save you trouble later.