Lotion Making Math & Ratio Guide

ratio graphic.jpg

I say it all the time but I’ll say it again.

I LOVE GETTING YOUR EMAIL QUESTIONS.

The teacher in me loves to answer questions.  I just love to help and spread knowledge!  I especially love when people ask me questions about topics we both love…like making beauty products!

Many of the questions I get are about math and proportions of ingredients.  In one of my favorite emails the author said she was “math challenged.”  Fear of math is pretty common.  I completely understand.  In this post, I’m going to quickly discuss how to do the math you need to make lotion.  It’s easy.  At the end, I will share an ingredient ratio guide for products.

Let’s do a quick lesson on percentages.

If a manufacturer says that a preservative is effective at 1% concentration, what do you do?  

If you are making batches of lotion to use at home, you’re probably making fairly small batches, probably no more than 20 ounces.  Measuring 1% of 20 ounces is easy.  First, move the decimal 2 places to the left.

1% becomes 0.01

Now you can multiply.

0.01  x  20 ounces  = 0.2 ounces of preservative

I don’t like using ounces because they’re not precise enough to me.  I like to use grams.  There are 28.3495 grams in an ounce.  So if you’re making 20 ounces,

20   x  28.3495  = 567 grams

0.01   x   567 grams = 6 grams of preservative

If a recipe calls for 60% water, you do the same thing.  First, move the decimal 2 places to the left.

60% becomes 0.60

0.6   x  20 ounces = 12 ounces of water

or, in grams

0.6   x  567 grams = 340 grams of water

Okay, good.  Now that we’ve gotten that out of the way, here is a great ratio guide.  The grams given are for making a batch that weighs 20 ounces/567 grams.

 ratiosandgrams

Notice that I called this a ratio guide, not a stone tablet of ratios.  You may change these.  One of my favorite body cream recipes doesn’t follow this guide too closely.  I wanted it creamier so I increased the butter and emulsifier, decreased the water, and left out thickener.  Please play with proportions!  If you ever want to write and customize your own recipes, you have to be willing to experiment with proportions.  That’s the only way to get information!

I hope this answers any math questions!  As always, please email hippiebrowngirl@gmail.com with questions.

9 thoughts on “Lotion Making Math & Ratio Guide

  1. Pingback: Body Cream Fit for a Queen | hippie brown girl

  2. Is the Preservative and Fragrance percentage included in the 100% or calculated from the meat and potatoes of the lotion like the items mentioned in your table?

    • Hey! Great question. It only includes the “meat and potatoes” (I like that). Once you’ve figured all these figures out, you can calculate how much preservative, fragrance, and antioxidant to include.

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