I don't know what's happening, but when I go to Disk Utility, my 1.5TB disk seems like only having 43MB of free space, when in reality, only 800GB or so are being used. Where are the other 700GB? If you do the math you will see that I'm not even close to 1TB, let alone 1.5TB... What may be causing this and how to fix it? Thank you!
I guess the extra storage space is taken yo by an APFS snapshot. You can view them by Disk Utility > View (on the left menu bar of Mac) > Show APFS Snapshots. Then Disk Utility will show you all the snapshots it created.
You can copy them to a desired drive as backup and use iBoysoft DiskGeeker to experience its Space Analysis feature to analyze your hard drive, seeing where all the largest files or folders are located, so that you can delete them to free up storage space.
This post is a macOS High Sierra download database. You can directly download macOS 10.13 installer file, DMG, and ISO for both supported and unsupported Macs.
A simple introduction to macOS stat command, including the key information and how to fix when it is not working on Mac.