I'm preparing to make by first salt bars. When I go to a lye calculator to enter my recipe, I don't see anywhere to enter the large amount of salt I will be adding (60% of oil weight). I understand that the addition of salt does not change the amount of lye needed. But by adding salt I'm greatly increasing the volume. I need a total soap batter of 500g for the mold I have so how do I figure this out? Sounds like this is a math thing rather than calculator. Thanks for any help on this.