Calculate NaOH for Cold Process Soap
โ ๏ธ Safety First: Always wear goggles and gloves when handling Lye. Add Lye to Water, never Water to Lye!
Making soap from scratch using the Cold Process method is essentially a beautiful chemistry experiment. The reaction that turns oils into soap is called Saponification. This process requires a strong alkali. For hard bar soaps, we use Sodium Hydroxide (NaOH), commonly known as Lye. Because every type of oil requires a different amount of lye to properly convert into soap, guessing is not an option. Too much lye will result in a harsh, skin-burning bar, while too little will leave you with a mushy puddle of oil.
Our Soap Lye Calculator uses standardized Saponification (SAP) values. For example, Olive oil has a NaOH SAP value of 0.134, meaning you need 0.134 grams of lye to turn 1 gram of olive oil into soap. The tool also incorporates "Superfatting" into the math. By default, soap makers leave a 5% superfat margin. This means we intentionally discount the lye by 5% so that some un-saponified oils remain in the final bar. These leftover oils are what make handmade soap so incredibly moisturizing and gentle on the skin.
AI-generated estimates. No guarantee of accuracy. We assume no liability for decisions based on these results. Independent verification is recommended.