Stud positions worked out so that sheet edges land on framing, which is the part people get wrong. The first stud is pulled back by half a stud thickness so the sheet breaks on the centre of the fourth stud rather than the edge of it.
Notes
Why the first stud is offset
Sheets are measured from the wall end, studs are measured to centres. If you set the first stud at a full spacing from the end, the sheet edge lands on the far side of a stud with nothing to fix to. Pulling the first one back by half a stud thickness fixes it.
400 or 600 centres
600 mm (24 in) uses fewer studs and is common for non-loadbearing partitions. 400 mm (16 in) is stiffer, better under tile or heavy cladding, and required in plenty of loadbearing situations.
Openings
Door and window openings need their own trimmers, cripples and a header sized for the load. That is a structural question and deliberately outside this tool.
What this does not do
It does not size anything structurally, and it does not tell you whether the wall can be built this way. It lays out a straight run.