Question: how do you know how much lye to use in soap?
Answer: Divide the amount of lye by 0.3 and then subtract the amount of lye from the result. For example, to make just over 2 pounds of olive oil soap, measure 32 ounces of olive oil and 4.33 ounces of lye because 32 ounces of olive oil × 0.1353, which is the saponification value for olive oil, = 4.33 ounces of lye.