One of the few cases there is something on a freshly formatted partition, is the ext3 fileesystem (Linux). There is about 5% of the total space, reserved for the root (to be able to operate the drive in case of full disk).
In the case of ntfs and fat/fat32, initially occupied space is very small, almost nothing.
I guess you mean that your partitions give a total of 695GiB or so, instead of the 750 GB the hard drive is marked. The truth is that the disk was really 750 billion bytes big. But the operating system makers and programmers, very badly, used to name 1024 bytes = "1 kilobyte", what is an error. 1 kilobyte (kB following the science and unit rules) is equal to 1000 bytes, no 1024. Further to this, they called 1024x1024 bytes = 1 "Megabyte", that is 1000000 bytes instead if 1048576 bytes. At the billions, this makes a distance of about 8% . There are no lost or locked bytes.
If you have already bought some specific models of seagate or western digital hard drives, you could participate in the trials some american attorneys begun just for this question. Perhaps you could win some new drive this manner (the attorneys will win some millions of $$$, of course). :LOL: Newer drive packages often contain a warning about this issue, to be legally covered.
In the Linux world and the open source community it is usual to use KB for 1000 bytes and KiB for 1024 bytes. Same, 1 MB for 1000x1000 bytes and 1 MiB for 1024x1024 bytes. Similar for GB and GiB.
*** It is highly recommended to backup any important files before doing resize/move operations. ***