Welcome to the Soap Calculator!

Please feel free to use this calculator any time you want to check the accuracy of your recipes or if you are creating a new one of your own.

Step 1: Set Total Recipe Weight

This step is optional. This feature is intended for those who want to create your own recipe. If you know the size of the batch you want to make, you can enter the weight in this step and you will be able to play around with the percentages of each oil you choose.  This step is not necessary if you already have a recipe you would like to check for accuracy or if you don't want to adjust the percentage of each oil.

Step 2: Enter the Lye Chemical

Sodium Hydroxide Lye is the default choice that is automatically displayed. Choose Potassium Hydroxide if you are making liquid soap.

Step 3: Superfat

5% is the default amount for excess oils, lye discount, or superfat. Set this option to 0% if you do not want to superfat or if you are making liquid soap.

Step 4: Enter Fats / Oils

Choose up to 7 of the different animal fats or vegetable oils listed in each drop-down menu and enter the weight of each one. To be able to adjust the percentage, you must first enter a total recipe weight in step 1.

Step 5: View Soap Properties

This area will display the overall properties of all the combined fats/oils. The blue areas represent what is generally considered ideal for each property.


This button will display your completed recipe.  Enter a name for your recipe in the box and it will be visible when you calculate the recipe.

Please note that this calculator uses average values and may not reflect the most exact measurements for the ingredients you are using. Saponification values naturally vary slightly, and this calculator is meant to provide reliable, but not exact, information. For exact figures, you will have to use the saponification values from the manufacturer of the oils you purchase and do some math by hand. For instructions on how to figure how much lye you will need for each oil by hand, please click here.

If you have any comments or suggestions, please feel free to email contact@howtomakesoap.org.

Thank You and Happy Soaping 🙂

Peace, Love, and SOAP! :)