I'm completely new to dual-booting Windows and Linux Mint. During the Mint installation, the partitioning screen shows two tiny areas of free space under the drive—just 1 MB and 0 MB—but Windows reports about 190 GB of free storage on my main SSD. Why doesn't the installer see that space, and what should I do before continuing?
3 Answers
The 1 MB and 0 MB entries are normal alignment gaps created when the drive was partitioned; they aren’t the large amount of space Windows reports as available. In Windows, open Disk Management, right-click the main Windows volume, choose the option to shrink it, and specify how much space to free. Then restart the Mint installer and select the new unallocated area.
Don’t delete random partitions or install into those tiny areas. First make a backup, disable Windows Fast Startup, and shrink the Windows partition from within Windows. Once the installer shows roughly 190 GB—or however much you chose to shrink—as unallocated space, you can use that for the Linux installation.
Windows showing 190 GB free usually means the existing Windows partition has unused space inside it. That is different from unallocated space, which is what the Linux installer needs. Shrink the Windows partition first using Windows Disk Management, then leave the resulting space unallocated for Mint. Back up important files before changing partitions.

The 190 GB is free space within the Windows partition, not empty space outside the partition. Shrinking it should turn some of that into unallocated space.