The soap calculator that
soap makers actually use.
SoapCalc has been the go-to lye calculator for handmade soap since 2001. Enter your oils, set your superfat, get exact lye and water amounts. 150+ oils in the database. No signup. No fees. Just soap math that works.
Exact Lye Calculations
NaOH for bar soap, KOH for liquid soap, or both for dual-lye recipes. Superfat and lye concentration controls built in. The math updates as you type.
150+ Oils & Fats
From coconut and olive to babassu and murumuru butter. Every oil has SAP values, fatty acid profiles, and soap quality predictions. Compare before you commit.
Soap Quality Predictions
See how your recipe scores for hardness, cleansing, conditioning, lather, and creaminess — before you make the batch. Adjust oils and watch the numbers change live.
Works on Your Phone
The old SoapCalc didn't. This one does. Responsive design tested on iOS, Android, tablets, and every screen size we could get our hands on.
How It Works
Pick your oils. Set your numbers. Get a recipe you can trust.
Pick Your Lye
NaOH for bar soap, KOH for liquid soap. One click.
Add Your Oils
Browse the database, compare fatty acid profiles, and build your recipe oil by oil.
Set Your Parameters
Water amount, superfat percentage, fragrance ratio. Qualities update live as you adjust.
View Recipe Summary
Exact lye, water, and oil weights in pounds, ounces, and grams. Print it. Export it. Make soap.
Three Ways to Make Soap
Whether you're melting a base or mixing lye from scratch, SoapCalc has you covered.
Cold Process
Mix oils with lye water at low temperatures, pour into a mold, cure for 4–6 weeks. Full control over every ingredient in the bar. This is what most soap makers do, and what the SoapCalc calculator is built for.
Learn about cold process →Hot Process
Same recipe as cold process, but you cook the soap (usually in a crock pot) until saponification is complete. Usable in days, not weeks. Rustic aesthetic. Same lye calculations as CP.
Learn about hot process →Melt & Pour
Start with a pre-made soap base. Melt it, add fragrance and color, pour into a mold. Done in under an hour. Great for beginners, kids (supervised), and quick gifts.
Melt & pour tips →Rebuilt From the Ground Up
The old SoapCalc ran on technology from 2002. It didn't work on phones. It went down without warning. The "new version coming Summer 2021" banner sat there for four years.
We heard every complaint. We read every forum thread. So we rebuilt the whole thing — modern framework, proper hosting, mobile support, and a team that actually gets notified when something breaks.
The math didn't change. Your recipes still work. Everything else got better.
Read the full story →Ready to make soap?
Open the calculator, pick your oils, and let SoapCalc handle the lye math.