My kilts are not made in a traditional way so I don't do waist and hip splits. I calculate the number of pleats based on hip size, apron width, and pleat width.

5cm is not quite 2 inches, so a fairly wide pleat. For most of my kilts I make the pleats roughly 1.5" wide, which IMO is a nice width for a casual, every day kind of kilt. If I'm making a fancy dress up kilt with a wider, more traditional apron width, I make the pleats roughly 1" wide.