That depends on the software Bacho. I don't really see how you can design class legal sails in a software package that doesn't give you sail area. I would bet good money that North, Quantum's and Doyle's in-house software gives you sail area, as does Smart Azure but I could be wrong. All my wing design tools generate area...now, the final product? That could still be different than what you drew for a myriad of reasons that you know waay more about than me.
Why Glaser can't provide this, I don't fully understand. They can measure F18 sails so they definitely can measure other class sails...but they should be providing the area. Its frustrating to me because we are working on a Nacra Inter 20 rules re-write locally that doesn't change the sail area but opens up the builder options, yet Glaser won't tell us the area of the sails they have built for the class (that we would like to make sure fit within the rules).
Ventucky Red, this is a helpful link: http://usf18.com/measurement-tips-and-pics/
I would also download the F18 measurement template. It has all the math built in for the diagram you have.