Measurements vs. Percentages in Soap Making Recipes

A Soap-Making Way to Look at Recipes

Homemade soaps with ingredients

Betsie Van der Meer / Getty Images

You are probably familiar with recipes that call for one cup of this, two tablespoons of that, or perhaps even a pinch of this, and so forth. You mix it up and pour it into a standard pot or pan and cook it. You may double or halve the recipe at some point, but the recipes are otherwise pretty standard.

What's the Difference Between Soap Making and Cooking?

However, in soap making, there are two things we do differently than in cooking.

The first major difference is that everything is weighed...even the water. This ensures that you're using the right amounts of every ingredient and that you're using the same measurement from batch to batch, recipe to recipe.

But let's say that you have a recipe that you like...and it says "6 oz. of this and 2 oz. of that." That's fine...until you want to change the recipe or modify it in some way. To really understand the recipe, to understand the qualities that the oils are going to give to your soap, you need to take things a step further and state your recipe in percentages as well as measurements - and this is the second way that soap making is different than cooking.

This doesn't mean that a standard recipe won't's just that writing the recipes this way is useful for a couple of reasons:

  1. It allows you to easily adjust the recipe to any size mold
  2. It allows you to easily adjust the proportions of the various oils in your recipe to affect the quality of the soap.

For example, let’s say you have a recipe that makes two pounds of soap. In it, you might have 1/2 cup of coconut oil. You try the recipe and the lather isn't as good as you'd like, so you'd like to increase the proportion of coconut oil. With measurements, this is hard, if you have percentages in addition to the measurements, it’s easy.

Converting a Recipe from Measurements to Percentages

We’ll start with a simple recipe (remember we're weighing everything, not using liquid measures.)

  • 12 oz. Olive Oil
  • 10 oz. Palm Oil
  • 9 oz. Coconut Oil
  • 8 oz. Canola Oil
  • 2.5 oz. Castor Oil
  • 2.5 oz. Cocoa Butter

This will make a 4 pound batch of soap. But what are the ratios of each oil? Is this a well-balanced recipe? And what if you want to make 7 pounds of soap?
Here’s what we do:

Total up the total number of ounces of oils. In this case, it’s 44. Divide each individual weight by 44 to get the percentage of that oil in the recipe.
12 oz. Olive Oil – divided by 44 = 27% (I’m rounding.)
10 oz. Palm Oil – divided by 44 = 23%
9 oz. Coconut Oil – divided by 44 = 20%
8 oz. Canola Oil – divided by 44 = 18%
2.5 oz. Castor Oil – divided by 44 = 6%
2.5 oz. Cocoa Butter – divided by 44 = 6%

So your recipe is:

27% Olive Oil
23% Palm Oil
20% Coconut Oil
18% Canola Oil
6% Castor Oil
6% Cocoa Butter
A pretty well-balanced recipe.

So let’s say you want to make a 7 pound (112 ounces) batch of soap. (Remember, that’s just the measurement of your oils. Leave room for the lye and water.) Multiply the percentage by the desired amount.

27 % Olive Oil x 112 oz. = 30.2 oz.
23% Palm Oil x 112 oz. = 25.8 oz.
20% Coconut Oil x 112 = 22.4 oz
18% Canola Oil x 112 = 20.2 oz.
And so on.

Now before you panic at all of the math, or think you need to create an Excel spreadsheet to make soap, relax. Most online lye/soap recipe calculators scale your recipes easily as well as give you the recipe in both measurements and percentages.

Now, whether you’re creating a recipe from scratch, or have found one online, you can both understand the proportions of the oils, and scale it to any size you like.