Soap Lye Calculator

If you’re formulating manually, you’d:

1. Look up the SAP value for each oil in your recipe.
2. Multiply each oil’s weight by its SAP value to find the required lye amount.
3. Add all lye amounts together.
4. Adjust for your chosen superfat level (usually 3–8%).

The Lye Calculator does all this instantly — no spreadsheets, no guesswork.

Our soap calculator supports:

• Cold process bar soap — Great for hard, long-lasting bars.
• Hot process soap — Allows for faster cure times.
• Liquid soap — Perfect for castile-style or specialty formulas.

Shop Soapmaking Oils & Butters:

• Olive Oil 
• Coconut Oil 
• Shea Butter 

The calculator also gives you the right lye-to-water ratio to ensure safe mixing. Always:

• Add lye to water (never water to lye).
• Wear gloves, goggles, and long sleeves for protection.
• Work in a well-ventilated area.

How to calculate lye?
Multiply each oil’s weight by its SAP value, sum the results, and adjust for your desired superfat level. The lye calculator automates this process and also provides water amounts.

The Lye Calculator is an essential tool for soapmakers — from beginners to seasoned pros. It removes the guesswork from saponification, ensuring your recipes are safe, balanced, and ready to impress.