Hard drive storage capacity

Couple of month ago I bought a new 1TB of hard drive. I experimented with different Linux distribution tried to find the best one. Now I am on Netrunner Frontier. But there is a little thing what I do not understand. Approximately 70 GB of storage capacity “disappeared” from the HDD. When I was reinstalling few different distribution I always created a new partition table. At time I did not listen carefully, just set up the root and swap partitions and all remaining storage capacity I gave to home partition. The problem is: if I open Dolphin file manager there are two partitions between “Devices”. One is 900 GB (home) and the other one is 24 GB (root). Why cannot I see the whole 1tb of storage capacity?

Maybe the swap partition is occupying the rest.
Keep also in mind that depending on your filesystem a short percentage is used for metadata and journaling.
And are you sure that its GB or TB or rather GiB and TiB ?

You’re right, of course that is GiB and TiB. I took a snapshot of the Partition Manager and attached it. It explains the issue better than I wrote it down.