At this point, you can get to work with your trusty tape measure, extending it across the length of all bathroom walls, and recording the size of each as you move along.
Then, repeat the process, this time marking the distance between the floor and the ceiling. Don’t forget to take alternate measurements where required, if the ceiling is at a different height in any part of the bathroom.
If you prefer, you can enlist professional help, or learn the ropes around some more advanced software to draw up 3D bathroom views, as opposed to a more simplistic floor plan such as this before making your dream bathroom vision a reality.
Of course, in any case, the extra expense of such a service will need to be factored in.