Scale is percentage scaling from the base square. The base square is 180x180 mm. So 100% scale would retain the 180x180 mm square. 150% scale would be 50% larger than the base square.
This post and Topic covers this as well:
Scale is percentage scaling from the base square. The base square is 180x180 mm. So 100% scale would retain the 180x180 mm square. 150% scale would be 50% larger than the base square.
This post and Topic covers this as well: