Quantity of hair required for each method..guide?

Hello everyone, was just wondering if there are guidelines or a table or something for reference on amount of hair needed by installation method?  If not, my specific question right now is for Elite Thermofiber, to do a full head (but not tooo full, my hair is fine and I don't want to suddenly be really full), thinking of using protac on Sherrie's rec....but how much to buy?  I'm not sure I understand the way the thermo is sold as I don't know if its for individual wefts that are cut or something else.  Sorry I'm probably missing some simple thing but I've been scanning the boards all lunch break and couldn't figure it out.  Someone please put me out of my misery!