There are many resources for us soap makers in the form of online calculators and phone apps. Here are some of my favorites! If you know of any that are missing from my list, please let me know in the comments!

Lye Calculators

Every oil that we soap with has a specific SAP (saponification) value. It takes a certain amount of lye to turn a certain amount of oil into soap. All oils are different! It takes a different amount of lye to turn olive oil into soap and a different amount of lye to turn castor oil into soap. This is why lye calculators are important. Sure, we can do the calculations by hand (and I encourage you to learn that), but using a lye calculator makes it more easy and less open to mistakes.

Most lye calculators work the same way. You enter the oils that you want to make soap with, you enter your superfat amount, hit calculate and it spits out at you the amount of lye and water that you’ll need for your recipe.

Here are some lye calcs available. Lye Calculator – My absolute favorite lye cal to use is the lye calc at Majestic Mountain Sage. It is a more simplified lye calc than many out there and doesn’t return to you an overwhelming amount of information. The inputs are easy and the page that it outputs is easy to read and print out. This is my go-to online lye calc.


Bramble Berry Lye Calculator – Bramble Berry has a great lye calc as well. The input is super simple and the output is easy to read and print.


Soap Calc Lye Calculator – It can’t be a post about lye calcs without me mentioning Soap Calc. I am actually not a fan of Soap Calc. I think this calculator is WAY to complicated, especially for new soap makers. I think it is easy to get hung up on the output and all of the different numbers that it spits out at you. I also don’t agree with all of the outputs.

How to Use a Lye Calculator

This video is part of my eCourse, Formulating Cold Process Soap Recipes E-Course. If you want to learn more about fatty acid profiles, soapmaking oils, creating recipes from scratch and modifying recipe, sign up!

Fragrance Calculators

Bramble Berry Fragrance Calculator – Bramble Berry has an awesome fragrance calculator. If you purchase their fragrances and want to know how much to use, simply fill out the form and it will tell you!


Apps for iPhone and Android

Bramble Berry Soap App for Apple or Android – I LOVE this app. I use it for the lye calc. If I’m making batch of soap and don’t want to run to my computer, I’ll just pull out my phone. This app has also helped us when teaching soap in developing countries with Lovin’ Soap Project. It does not require internet to run the calc. So once we find materials in the local markets, we are able to use the lye calc. Most of the time we don’t have access to internet, so this app has literally saved our project on more than one occasion.


These are my favorite online calculators and apps! I’m sure there are more out there. What is your favorite online calc or app? Please share in the comments.

Happy Soaping!

-Amanda Gail