Soapy Math Part 4: Understanding Percentages

*CORRECTION* Please note that I swapped the SAP values of Shea Butte and Palm Oil by accident on the last practice problem. Here is the correct math if you use the correct SAP values. Lye Discount (Total Amount of Lye) x (Discount) = (Lye Discount) (Total Lye Amount) – (Lye Discount) = (New Lye Amount) Our recipe calls for 4.08 oz. of lye and we want a 5% lye discount. We can plug that into our equation: 4.08 oz. x 0.05 = 0.204 oz 4.08 - 0.203 = 3.876 oz. Lye Calculating Water Amounts (Amount of Lye) / 0.3 = (Total weight of Lye Water Solution) (Total Weight of Lye Water Solution) – (Amount of Lye) = (Amount of Water) Our recipe calls for 3.88 oz of lye. So, we can plug that into our equation: 3.88 oz. / 0.3 = 12.93 oz 12.93 oz. - 3.85 oz. = 9.08 oz Water ----------------------------------------------------- Why bother doing soapy math by hand when we have the use of lye calculators to do the calculating for us? Well, because that lye calculator will only get you so far! There are a variety of math calculations you need to understand to formulate, create, and troubleshot recipes. #soapymath #calculatingarecipe #coldprocesssoap #calculatingyourlye #percentages #lyediscount I've divided this lecture into a four part series. This is the final video of the series. If you missed the first three go check those out first! The goal of these videos is to teach you how to calculate a recipe from scratch and in turn help you understand what each element of a lye calculator does. So, let's get started! HANDOUT Available for purchase: https://jennifersoap.com/collections/... PART 4: UNDERSTAND PERCENTAGES Understanding how percentages work when calculating a recipe is very important. I’m sure you’ve seen recipes that look like this: 20% Coconut Oil 20% Palm Oil 50% Olive Oil 10% Shea Butter What does this mean though if you want to convert the percentages into ounces so you can make soap? First step is to convert the percentage into a decimal. So you take the percentage and divide it by the total percentage of all items. In this case: 20 + 50 + 20 + 10 = 100 20 / 100 = .20 50 / 100 = .50 20/ 100 = .20 10/ 100 = .10 Once you’ve converted the percentages you can then determine the amount of oil you’ll need. You simply take the weight of the batch and multiply it by the converted percentage. With that in mind let’s go back to the problem on hand. Let’s say we have a total weight of oils of 28oz. We take that and multiply it by each percentage. .50 x 28 = 14.0 .20 x 28 = 5.6 .20 x 28 = 5.6 .10 x 28 = 2.8 If we did our math right then 14 + 5.6 + 5.6 + 2.8 should add up to 28. Now you can take the ounces and plug them into a soap calculator to calculate the amount of water/lye you’ll need—or you can do it by hand. Part 2 Now if you understand this then you can calculate recipes even if you just know the weight of one of the oils! Let’s assume that we were told olive oil makes up 14 oz of the recipe and we know that olive oil is 50% of the recipe. Before you can proceed you have to determine the total weight of oils this recipe will make. If olive oil is 50% then we need to account for another 50% in oils. Simple math tells us that if half is 14oz then just add another 14oz (double 14) to it and the total weight if the recipe is 28oz. Now that we know this we can apply the same method as above: .20 x 28 = 5.6 .20 x 28 = 5.6 .10 x 28 = 2.8 Part 3 Okay, now that you understand that I’m going to make it harder! What if it’s not “simple math” and you can’t go “oh I know 50% is half”? Then just set up your problem as an algebraic equation: Let’s look at a NEW recipe. An oil blend is to contain 50% olive, 20% palm, and 30% coconut. How many pounds of olive oil should be used with 8 pounds of coconut oil? What your recipe has: (converted to decimal) 50% olive oil (.50) 20% palm oil (.20) 30% coconut oil (.30) What we KNOW for actual weights of oils: 50% olive oil = ? 20% palm oil = ? 30% coconut oil = 8lb Let’s set it up as an algebraic formula: You need to determine: 8lb is 30% of what (x)? So, 30% = .30 8lb = .3x (x represents the total weight of the batch) Then just solve the formula: (to get “x” on its own you have to divide each side by .3) 8/.3 = .3x / .3 (the .3 cancels out leaving you with just “x”) x = 8/.3 x = 26.6 Now that you know the TOTAL weight of the recipe you can calculate 50% olive oil. 50% x 26.6 (convert the 50%) .5 x 26.6 = 13.3lb --------------------------------------------------------------------- Jennifer's Handmade Soap - Because soap should be more than just functional! Webpage: www.jennifersoap.com Facebook: www.facebook.com/JeniferSoap Instagram:   / jennifer_soap   TikTok:   / jennifersoap