How to use Percentages in a Recipe October 06 2017, 0 Comments
I think one of the most common questions we receive is "How do I use a recipe that is only in percentages and why are recipes be weight instead of volume?"
The only time a weight and a measurement, ie 1 gram and 1 milliliter, are the same amount is when weighing/measuring water. For every other ingredient, 1 gram DOES NOT EQUAL 1 ml. Therefore, one teaspoon of glycerine does not weigh the same as one teaspoon of water. Because of this, recipes in measures (teaspoons, tablespoons, cups, etc) are often doomed to failure. Further, give 5 people a measuring cup and ask them to measure out 1 cup of an ingredient. If you take those 5 cups and now weigh them, you will get 5 different weights. It's not because those 5 people can't measure, but rather because even if you get down to eye level to look at the thin red line across the measuring cup it is very difficult to line up exactly to the line. This discrepancy leaves us with a very good chance of having a recipe fail.
Now let's say you've got a recipe in measurements that seems to work for you. What happens if you find a cool new ingredient you want to add? How do you figure out how much to add to your teaspoons/tablespoons/cups? The usage rates for ingredients are always given in percentages, not measures, so now it's pretty much impossible to determine the correct amount to use in teaspoons/etc. Or what if you have a nifty new bottle but it holds more or less than the amount your recipe makes. How do figure out to increase or decrease your recipe so that it fits in that nifty bottle?
We weigh our ingredients so the amounts will be accurate and our recipe will not fail, but more importantly so we don't use too much of an ingredient that may cause irritation if the amount is too high (ie. hyaluronic acid, preservatives). Or, if we don't add enough of say, our preservative, we have nasties growing before long, and we have to throw out our lotion.
We use percentages in a recipe to determine the weight of each ingredient and this makes is super easy to increase or decrease our batch size! People seem to be really worried that there is some very complicated math involved in this, and when they come to the store and we show them how to do the math, they are surprised at how simple it really is!
Let's look at a basic lotion recipe from Swift Crafty Monkey:
Heated Water Phase
Heated Oil Phase
3% Cetyl Alcohol
Cool Down Phase
1% fragrance or essential oil
Let's say we want to make 120 grams. Note that we want GRAMS which is not the same as milliliters. It's close, but not exact.
The math works like this:
Water: 120 grams x 69% = 82.8 grams
Oil: 120 grams x 15% = 18 grams
Butter: 120 grams x 5% = 6 grams
Cetyl Alcohol: 120 grams x 3% = 3.6 grams
Emulsifier: 120 grams x 6% = 7.2 grams
Fragrance: 120 grams x 1% = 1.2 grams
Preservative: 120 grams x 1% = 1.2 grams
That's all there is to it! Now your recipe is in grams, and your batch will weigh 120 grams total.
What happens if your recipe has a lot more ingredients? Yes, there's more math. But if you have Excel, click this link to "purchase" our FREE recipe calculator. Once you've filled in your ingredients, this will allow you to quickly change your batch size. You can also easily change your recipe. Just remember to save or print a copy!
As always, we love to hear from! If you have questions or comments, you can reach at firstname.lastname@example.org.