Yes, this is correct. People usually end up with a lot more loss during fermentation than they expect. The finished beer field is how much drinkable beer you want to end up with. Fermentation trub is how much you leave in the fermenter. I assume that most people will try and transfer as much as possible from the kettle to the fermenter. Kettle trub is calculated based on hop absorption. It's not perfect but it tends to get pretty close.Calvey, Not sure I agree. Since the calculator is asking how much beer you want to end up with, the trub loss is actually a calculation of any loss in the system. I could be wrong but this is how I use it and I hit my finished beer volumes right on.
Everyone has a different process. You can't really compare how hard one person squeezes the bag compared to another. The calculator assumes no squeezing. Just a lift and drain. I've been meaning to update it with some "fudge" numbers so that people can dial in their systems a bit.I've had good sucess using it many times but I find it gives me about .5 gal. to much water to start with. I assume it's the numbers I put in or my system, not the calculator it self. Either way, it's a great help.