Image: Lab scale
Image: Lab scale

Grams vs. Ounces for Making Soap

Grams or Ounces is a Personal Choice

This is entirely an individual choice. Many soapmakers, however, prefer grams to ounces for various reasons. Some believe that their scale gives a better precision in grams because a gram is a smaller unit than an ounce. Some like to work with whole numbers rather than decimals. And some are simply used to the metric system.

All are valid points. I will give you my reasons for my preference for grams over ounces.

Why Grams for a Soap Recipe?

  1. Better precision rounding up or down.
  2. Easy conversion from percentages to weights and back.
  3. Good soap amounts for a manageable mold.

Let me explain.

Better precision rounding up or down.

Many believe that using grams for the weights of oils, water, and lye gives a better precision on the scale. After all, one gram is practically one-thirtieth of an ounce. Obviously, a decimal of a gram gives a better precision unit compared to a decimal of an ounce. Most scales, however, give you the same weight whether it’s in grams or ounces. If your scale precision is one decimal for a gram, it’s two decimals for an ounce.

The difference, however, is in how the numbers are rounded. We were taught in school to round up a fraction of 0.5 or higher and down if it’s 0.4 or below. So, if you round up 1.5 oz to 2, your gram equivalent will be 42.5 g to 56.7g, respectively. That’s a pretty big difference in grams. While it’s hard to perceive this difference in ounces, you can definitely see it in grams.

That’s why grams are preferable for me.

How important are gram decimals in soapmaking? Not very important. There are always losses of oils in soapmaking. Large bowls, for instance, are coated with oils. You can be very thorough in scraping them off, but it’s practically impossible to gather 100% of the oils. The utensils are dripping with oils, and so on. This is one reason, that I always round up my oils in the recipe. (The other reason is that I prefer to err in the direction of super fat for safety.)

So, I choose grams over ounces in soapmaking because they give me a better precision when rounding numbers and a better perception of the amounts.

Easy Conversion from Percentages to Weights

The other reason for choosing a gram unit is an easy conversion between percentages and weights. Most of my soap recipes are designed in percentages, not weights. The only exception is when I have a leftover of a valuable oil/fat that I want to incorporate into a recipe. In this case, I weigh my leftover in grams and use that measure for the recipe. It’s also easy to convert grams of the leftovers to percentages.

So, how is the conversion easy? Let me demonstrate using the sunflower oil and deer tallow soap recipe.

One kilogram of soap is equal to 1,000 grams. One percent of 1,000 is 10 grams. All you have to do now is multiply your percentages by 10 to see the amount in grams.

In the sunflower oil and deer talow recipe, for example,

  • the proportion of sunflower oil is 15% or 150g for a kilo of soap;
  • 30% of deer tallow is 300g;
  • finally, 55% of olive oil makes it 550g.

Isn’t this easy?

And the other reason for choosing, gram units is that they give me very convenient soap amounts.

Good amounts of soap for a manageable mold.

One kilogram of soap is an easy amount to make. You can divide by two to make 500g or multiply the amount to make more soap.

Obviously, the amount depends on how many people will be using it, the size of your mold, and so on. But first, let me share with you one more sweet little tip about the molds. A quart carton from Half-and-Half or a whipping cream makes a nice, convenient, and disposable soap mold. I love them!

Image: homemade soap in a recycled container
Soap made in a recycled cream container.

First of all, it’s free! And you get to recycle the carton. That’s nice.

Second, this carton is coated with wax on the inside. This coating makes the next-day removal of your soap very easy.

And third, this little carton holds approximately 500 grams of soap. If you make two cartons at a time, that’s 1,000 grams or a kilo. You can see all your percentages from any recipe very easily.

Image: homemade soap
Homemade soap out of favorite mold.

If you want to be more precise with your soap molds, however, you can read my explanation on resizing your soap recipe to fit the mold here.


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