The easiest way to superfat is not to add any extra oil but to use less lye . Soapcalc's superfat is set to 5% , that means you will use 5% less lye than is needed to saponify your oils . The calculator will tell you exactly how much lye and water to use with the size of batch you want . Most of the oil added after the superfat would be eaten by the lye monster anyway . You don't run the risk of forgetting to add the oil this way either . Good luck with your first batch