Free Lye Calculator

SAP (Saponification) value is the amount of lye needed to completely saponify 1 gram of a specific oil or fat. Different oils have different SAP values, which is why accurate calculations are essential for successful soap making.

NaOH (sodium hydroxide) is used to make bar soap, while KOH (potassium hydroxide) is used to make liquid soap. KOH requires approximately 1.4 times more lye than NaOH to saponify the same amount of oils.

Most soap makers use 5% superfat as a starting point. Lower superfat (3-5%) gives harder, longer-lasting bars. Higher superfat (6-8%) creates more moisturizing soap but may reduce lather and shelf life.

Look at the soap properties: Hardness 29-54, Cleansing 12-22, Conditioning 44-69, Bubbly lather 14-46, Creamy lather 16-48, Iodine 41-70, INS 136-170. This calculator shows where your recipe falls within these ranges.