I think my love for soap making elevated to the next level when I learned how to concoct my own, original recipe. I was intimidated at first but once I learned the basics, coming up with a unique recipe made the process 10 times more fun! You can whip up a soap in any color, scent, size, and effectiveness you want. (You want to make a peppermint-scented moisturizing soap with oatmeal bits for exfoliation? No problem!) There’s nothing more gratifying and pampering than lathering up a soap that you created, just for your enjoyment. 
I summarized the basic steps in how to create your own, one-of-a-kind soap recipe here! The post is a bit lengthy and some parts may appear a little technical, especially around the water and lye calculations, but everything is straightforward. Please don’t be discouraged — you’ll be reaping your reward in no time!
Just a disclaimer before we proceed. This post is intended to show new soap makers who are interested in concocting their own original formula the basics of creating their own suds. It is not intended to provide expert advice on the usage of lye (sodium hydroxide), essential oils, and other complex properties. I encourage you to browse through books and the Internet to learn the more technical aspects of soap making! Afterall, soap making is not just an art but also science and it should be treated as such. Also, the use of lye can make soap making potentially dangerous, so please proceed with caution.
With that said, let’s get started!
The Formula Spreadsheet
What you see here below is a sample Excel spreadsheet that I use when I’m developing a new recipe, to calculate the oil, water, and lye amounts. Don’t worry if these numbers make absolutely no sense to you at the moment. You’ll be an expert by the time you finish reading this post.
I’ll use this Avocado Soap spreadsheet throughout this post to explain each step.
Figure 1: Avocado soap recipe spreadsheet sample
Step 1: Determine the Batch Size
The first step is to decide how big your batch is going to be. It’s an equivalent of knitters deciding on the project pattern. I typically use a one quart milk carton, which holds about 600 grams of fats (which are oils and / or butters). I make two of those milk cartons at a time, and thus my recipe is for 1200 grams.
Note: The carton you see here is for one, 600 g batch. If you want to make just one carton worth of soap, and not two as the recipe indicates, simply divide the amount of all ingredients in half.
Step 2: Select Your Ingredients
This is my favorite part of the soap-making process. It’s very similar to crafters deciding on what fabric or yarn to use for the next project. It allows you to be creative!
The best part about making a soap at home is that you can customized it to however you want, depending on your current need. If you are suffering from dry skin, you can incorporate oils and butters that have the moisturizing properties. If you want a soap that smells like refreshing fruits when lathered in the shower, add citrus essential or fragrance oil.
Note: I usually purchase oils and other soap-making supplies from Bramble Berry, Cibaria,From Nature with Love, and Mountain Rose Herbs. They are all wonderful. I buy oils in bulk but you can find olive oil, coconut oil, and other lovely oils and fats in smaller portions at places like Whole Foods Market and Sprouts Farmers Market.
Step 3: Determine the Amount of Fats Needed
Steps 3 (Determining the Amount of Fat Needed), 4 (Determining the Amount of Water Needed), 5 (Determining the Amount of Lye Needed), and 6 (Determine the Lye Discount) require you to do a little math, but don’t worry if you haven’t done any number crunching beyond balancing a checkbook since high school. 
The calculations are pretty simple.
Let’s begin by deciding how you want to allocate your selected fats (column C).
Figure 2: Fat allocation percentages
By the way, when I say “fats,” I’m referring to any oils and / or butters used in this recipe. In the case of this Avocado Soap, I wanted to make a gentle soap with moisturizing power, so I allocated 40% of my fat to be avocado oil (column C, row 4), 30% olive oil (column C, row 3), 10% shea butter (column C, row 5), 10% palm oil (column C, row 6), and 10% coconut oi (column C, row 7). They should all add up to 100%.
Now, convert the fat percentage into an actual weight in gram (Column B).
Figure 3: Avocado oil amount needed
Let’s use the avocado oil for example. To calculate 40% of 1200 gram:
1200 g x 0.4 = 480 g
This means that I would need 480 g of avocado oil (column B, row 4) for this recipe. Do the calculation for the rest of the oil and dd them all up. The total should add up to 1200 g.
Step 4: Determine the Amount of Water Needed
Now, it’s time to figure the amount of water needed.
Figure 4: Amount of water needed, in gram
For this recipe, I used the ratio of 72 (fat) to 28 (water). This means that 72% of the entire weight will be fat, and 28% water. To calculate 28% of 1200 g:
1200 x 28 / 72 = 466.67
In this case, the amount of water needed is 466.76 g (column B, row 8). You can certainly round the number off to 467 g.
Note: You can substitute part of water with other liquid to create a more complex soap. I like to use aloe vera juice and yogurt in my soaps. However, some substitutes such as milk can produce a strange odor (it luckily disappears once the soap is cured) and others may change color.
Step 5: Determine the Amount of Lye Needed
Let’s calculate the amount of lye needed, shall we? This one’s a little tricky but stay with me.
You can figure this out two ways – manually or by using an online lye calculator. Many soap-making Websites, such as Bramble Berry, has an online calculator where you simply plug in the weight (gram or ounce) or the percentage of fats and it figures out the lye amount for you. This is probably the easiest and the best way to do this.
If you want to figure it out manually, need something called Saponification Chart that shows Saponification Numbers. It’s overly technical for me to explain this properly 
but in layman’s term, these numbers allow us to figure out the amount of lye needed to convert one gram of fat into soap.
Figure 5: Saponification Value
The amount of lye needed differs by oil. For example, the amount of lye needed to convert avocado oil into soap (0.14) is not the same as, say, shea butter (0.13).
Figure 6: Amount of lye needed to convert avocado oil into soap
Let’s take a look at avocado oil for this example. The lye needed to turn one gram of avocado oil into soap is 0.14 g (column D, row 4). Since there’s 480 g of avocado oil (column B, row 4), you need to calculate this by multiplying the lye weight (column D, row 4) by the total fat weight (column B, row 4).
480 g x 0.14 g = 65.76 g
You need 65.76 g of lye to convert avocado oil in this recipe to soap (column F, row 4).
You need to calculate the lye weight for all the fats used. After you figure them out, add them together. The total is the amount you need for the entire batch.
Figure 7: Total amount of lye needed to convert all fats into soap
Take a look at column F. When you add rows 3 (olive oil), 4 (avocado oil), 5 (shea butter), 6 (palm oil), and 7 (coconut oil), you get 170.16 g (column F, row 7). That’s the amount you need to convert all the fats used in this recipe into soap.
Step 6: Determine the Lyle Discount (optional)
Now, let me throw you a curve ball and talk about something called a “lye discount.” In a nutshell, lye discount is the amount of lye you’re doing to reduce from the total amount to create a milder soap. This step is completely optional but I usually discount in my soap creations.
Figure 8: Total amount of lye needed to convert all fats into soap, after discount
For this recipe, I wanted to reduce the lye amount by 15%, thus making lye discount at 85% (100% – 15% = 85%). To determine the lye discount, take the total lye amount and multiple it by the percentage:
170.16 g x 0.85 = 144.64 g
I rounded up the total to 145 g (column B, row 9). This is the final lye amount used for this recipe (reduced from original 170 g to 145 g). YAY — you’re done with math now!
Step 7: Determine the Additives (optional)
You can enhance your soap with lovely aroma, color, and texture by adding special embellishments.
Scents:
Essential oils are great for adding both scents and healing properties. My absolute favorite is lavender, and I use it in every soap I make. The scent relaxes me and uplifts my mood and spirit!
Fragrance oils are another great way to add a special scent to your soap, but unlike the essential oils that are extracted from plants and are natural, they are synthetic (how else can you explain scents like Sugar Plum and Bubble Gum? ). I think it’s completely up to you to decide which route you want take. My soaps are mostly all natural, but once in a blue moon, I enjoy making playful, Lush-like suds loaded with fun and crazy scents.
Dry Additives:
Dry herbs are great for many reasons. It gives your soap a unique look, while working as a great exfoliate. You can use grounded oatmeal, lavender, chamomile, peppermint leaves, etc.
Take a look at how dry herbs can give a different feel to each soap.
Colorants:
Handmade soaps tend to lose its color pretty quickly so adding a colorant can help maintain the lovely hue for a longer period of time. It’s great for creating colorful designs too. Here’s my first attempt at creating tri-color layered soaps, using madder root power (for pink) and comfrey root powder (for green). I’m dying to try carrot soap, with a nice orange shade soon!
Summary
Thank you for reading this long post! I hope this piqued your interest in creating your own, special soap! Please also check out my handmade soap tutorial by clicking here!
I think we’ve all hear of this phrase:
Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime.
I feel like that when it comes to soap making. I can rely on other people’s recipes to make soaps and limit myself, or I can learn how to create my own and open up the endless possibilities. It’s empowering, and I love to know that I’m creating something that’s truly one of a kind.
I hope to continue to learn more about this fascinating world of soap making, and take the Lavender and OliVE soap business to the next level. I’m still in the development stage but I’m hoping to start spreading my handmade soaps to the masses, via Etsy and local craft fairs very shortly! Pleas stay tuned! 
