How to use the Cosmetics Lab Soap Calculator

To make soap using the cold process method, you’ll need to mix specific fats or oils with lye (also known as caustic soda) following a precise procedure.
The Cosmetics Lab Soap Calculator is a user-friendly tool that helps you determine the exact amounts of each ingredient by making precise calculations of proportions, ensuring reliable results every time.
In this tutorial, we’ll walk you through how to use its features to confidently craft your own custom soap recipes!

Contents at a Glance

Below is a quick overview of the topics covered in this guide. Click on any of the links to jump directly to the corresponding section:

• Introduction
• Detailed explanations at every stage
• Levels of expertise
• Navigating through wizard steps
• Bars of soap or liquid soap?
• Water: how much?
• Amounts of fats and oils
• Superfatting
• Selecting fats and oils
• Essential oils, fragrances, herbs and other additives
• Adding a recipe title and notes
• Viewing the recipe results
• Printing your recipe

Introduction

If you’re new to cold process soap making, I recommend reading a tutorial on how to make soap using the cold process method.
Once you’re familiar with the basics, here’s what you’ll need to do next:

• Choose the fats or oils for your recipe. This decision depends on the properties you want your soap to have (e.g., conditioning, lathering) and is largely a matter of personal preference.
• Set other parameters, such as the amount of water, superfatting percentage, and total batch size.

The Soap Calculator allows you to set or select all the above parameters through clear, user-friendly steps.
Note: If you’re ever unsure about which value to select, simply use the suggested default value.

Detailed explanations at every stage

If you need help or an explanation at any stage, simply click the "?" icon at the top of each card (or anywhere in the card header!). This will expand a section with detailed information about the current step.
To collapse an expanded information section, click again at the "?" icon (or anywhere the card header).
Note: in wizard modes (Beginner and Intermediate), the help sections are already expanded for your convenience.

Levels of expertise

To cater to different levels of expertise in soap making, the Cosmetics Lab Soap Calculator offers three distinct user interfaces.

• "Beginner": If you’re new to soap making, select this option. A step-by-step wizard will guide you through the process, providing detailed explanations at each stage. Many values are pre-selected to minimize the number of decisions you need to make, making it ideal for those just starting out.
• "Intermediate": If you have some experience with cold process soap making, this option is for you. It also uses a step-by-step wizard but includes more steps, giving you full control over every parameter in the soap-making process.
• "Expert": Designed for seasoned soap makers, this mode presents all parameters and options on a single page. This allows for quick and efficient selections without navigating through the wizard’s "next/previous" interface.

Navigating through wizard steps

If using the step-by-step wizard (Beginner or Intermediate mode), click buttons Next/Back to move between steps.
IMPORTANT: Do not use your browser's "Back" button to navigate to the previous step.

Bars of soap or liquid soap?

• If making bars of soap, select "NaOH".
• If making liquid soap, select "KOH".

Note: In the "Beginner" wizard mode, this step is omitted. It is assumed that you'll be making bars of soap.

NaOH/KOH purity:

• This refers to the purity percentage of your lye, typically ranging between 98% and 100%. Your supplier should provide this information. The purity level is used to calculate the exact amount of lye required for your recipe.
• If you are unsure about the purity of your NaOH or KOH, simply use the recommended default value of 99.8%.

Water: how much?

Note: In the "Beginner" wizard mode, this step is omitted. The amount of water is pre-selected for you.

The amount of water used to dissolve the lye plays a crucial role in the soap-making process. It affects how quickly your soap thickens (reaches "trace"), when you can cut it, and how fast it dries (cures). This amount is typically expressed as a percentage, representing the ratio of water to the total weight of oils/fats in your recipe.

While you can use water percentages within the range of 22% to 40%, we recommend choosing a higher percentage (above 33%) if you’re new to soap making (the default recommended value is 38%). A larger amount of water gives you more time to work with your soap before it reaches trace and is more forgiving in case of errors or delays.

Even for experienced soap makers, a higher water percentage is recommended when:

• Trying a new recipe for the first time.
• Using a fragrance or essential oil for the first time, as some fragrances/essential oils can accelerate thickening, making it difficult to pour the soap into molds - especially if the water percentage is low.

Alternatively, you can express the amount of water as a "water-to-lye ratio" (some soapmakers prefer this method). In this case you need to provide two numbers, the first of which representing the water and the second the lye.

Amounts of fats and oils

The Soap Calculator requires you to input the amount of each fat or oil in your recipe. There are two ways to do this:

1. Specify the total weight of all fats and oils (in your preferred unit, e.g., pounds or grams), and then indicate the amount of each fat/oil as a percentage of the total weight.
2. Specify the weight of each individual fat or oil (in your preferred unit, e.g., pounds or grams).

Below we'll explore each scenario in detail.

Scenario 1: Specify the total weight and indicate the percentage of each fat or oil

If you're unsure of the total weight of oils to use but you know the dimensions of your mold (or the weight of soap it can hold), click "Input mold size" for assistance in determining the correct amount. In the pop-up window that appears:

• If you know the total capacity of the mold (e.g. it can hold 2 kilograms of soap), select "The total capacity of the mold" and input the capacity along with your preferred unit of measurement.
  
• If you know the dimensions of the mold, select "The dimensions of the mold", specify whether your mold is rectangular or cylindrical, and input the dimensions along with your preferred unit.
  
• Then, click "Calculate size" and the total weight of the fats/oils will be calculated and filled in the appropriate box for you.

Scenario 2: Specify the weight of each individual fat or oil
In this case, all you need to do at this stage is select your preferred unit of weight. Later, when selecting the fats and oils, you’ll be prompted to input the weight for each one individually.

Superfatting

Note: In the "Beginner" wizard mode, this step is omitted. A default value is pre-selected for you.

If part of the lye does not react with the oils and remains in the soap after the saponification, the resulting soap can be caustic and harsh to the skin. To prevent this, most soapmakers use an excess of oils and fats in their recipes - more than the amount theoretically required to react with the lye. This process is called superfatting. You may also hear the term "Lye discount", which is essentially the same concept.

Superfatting also benefits the skin as the excess of oils in the soap create a protective, moisturizing layer.

Superfatting is expressed as a percentage, typically ranging between 1-10% (with the recommended value around 5%). However, many soapmakers use significantly higher superfatting percentages. Keep in mind that:

• Higher superfatting results in a softer soap and reduces lather production.
• Soaps with higher superfatting are more prone to going rancid over time.

We recommend experimenting with different superfatting percentages to find the right balance for your preferences and needs.

Selecting fats and oils

The fats and oils you choose will determine the properties of your soap, such as lathering, conditioning, creaminess, and more.

To add a fat/oil to your recipe:

• Browse the list,
• or, type a few letters in the search box to filter the list and display fats/oils that match your input.
• Click on the fat/oil you want to select it.
• Enter the percentage (or weight) for this fat/oil in the corresponding text box.

Note: If you’re entering quantities as percentages, ensure that the total sum of all percentages equals 100%.

Selected fats/oils are highlighted with a colored background in the list.

To remove a selected fat/oil:

• Click on it again in the list, or
• Click the "x" button on the right side of the selected fat/oil.

Essential oils, fragrances, herbs and other additives

Optionally, you may want to include additional ingredients, such as fragrances, essential oils, or herbs. For simplicity, I’ll use the collective term "additives" to refer to all these ingredients.

To add an additive to your recipe:

• Browse the list,
• or, type a few letters in the search box to filter the list and display additives that match your input.
• Click on the additive you want to select it.
• Enter the amount for this additive in the corresponding text box and select your preferred unit (e.g. pounds, ounces, ml, drops)

Selected additives are highlighted with a colored background in the list.

To remove a selected additive:

• Click on it again in the list, or
• Click the "x" button on the right side of the selected additive.

Adding a recipe title and notes

You can name your recipe by entering a title in the appropriate field.
You can also add any additional details about this recipe, such as custom additives you've used or important notes about the process or specific recipe. Use the 'Notes' field to record this information.

Viewing the recipe results

Once you've made all your selections, the Soap Calculator is ready to generate the results. Click the 'View Results' button to access a summary of your selections, the calculated amounts, and the title and notes for your recipe.
See the image below for a preview of the results page.

Printing your recipe

Once you've finalized your soap recipe, click the "Print" button to print it.
If you click the dropdown arrow next to the "Print" button, you'll see a "Print Options" menu item. Selecting it opens the "Print Options" dialog.

In this dialog, you can choose which cards to include or exclude from printing by checking the appropriate boxes.

You'll also find an "Ink Saving Mode" option, which significantly reduces ink or toner usage when printing graph bars.
The images below illustrate the difference between normal printing and ink-saving mode.

Normal print mode

Ink-saving print mode