Base Carrier Oils: The Heart of Your Homemade Soap

The world of soap making is a realm of creativity and self-expression, where you can transform ordinary ingredients into luxurious lathers that pamper your skin. At the heart of this process lies the selection of base carrier oils, the foundation upon which your soap masterpiece is built. Base Carrier oils play a crucial role in determining the properties of your soap, from its hardness and lather to its moisturizing and conditioning effects.

Understanding Base Carrier Oils

Base carrier oils are the main ingredients in soap making, providing the essential fats and nutrients that nourish and protect your skin. They are typically derived from plant sources and contain a variety of fatty acids, each with its unique properties. Some oils are known for their emollient qualities, leaving skin feeling soft and supple, while others are rich in antioxidants and vitamins, promoting skin health and vitality.

In this chapter, we will review the different types of fats and base carrier oils that are used to make soap. The four major kinds of fats and oils that we will use are tallow, lard, olive oil, and coconut oil. When they are combined, they create hard bars that can be either cleansing, bubbly, creamy, or conditioning, or some combination of all four. After deciding on one or all of these bases, you will then add other oils to ensure that your bar is exactly how you want it.

For example, if you want to make an olive oil soap, you will need to use a harder oil along with it or else you will wind up with a very soft soap. If you use only coconut oil in your mixture, your skin may become dry.

We will help you understand how you can combine your base carrier oils to make wonderfully nourishing soap bars. There are some oils you will not see listed below. Some of them were omitted because they are genetically modified or not ethically grown and processed. Others, like rice bran oil, can sometimes cause difficulties when used for soapmaking. Since we want you to have successful experiences, we have chosen oils that are easy to use and accessible.

In the following list you will see that we give the SAP value for each oil. You can use the SAP value to determine how many ounces of lye are needed to convert 1 ounce of oil into soap, but rest assured that online lye calculators will also do the job for you. Note that the SAP value I give you is for sodium hydroxide, not potassium hydroxide.

Using SAP Value

In order to determine how much lye to use, multiply the SAP value of the oil you are using by the amount. For instance, if we are using 6 ounces(180 ml) of apricot kernel oil (SAP value: 0.139) in my recipe, we need to multiply 0.139 × 6 = 0.834.(0.139 x180ml = 25.02) That means that we need 0.834 ounce(25.02 ml) of lye to saponify the oil. We make this calculation for each of the oils in my recipe. Remember, every oil is different and therefore needs a different amount of lye.

Once we have calculated the amount of lye needed, We still need to take away at least 5 percent of the lye so that we have oils leftover in my soap for nourishment. We call this superfatting, or lye discounting. The traditional lye discount used is 38 percent of the oil in the recipe. For example, a recipe with 34 ounces (1020 ml) of oil will need 12.92 ounces(387,6 ml) of water (34 x 0.38 = 12.92)  (1020ml x 0.38 = 387,6ml).

But you don’t have to do all this work yourself every time you want to substitute an oil or create a new recipe! As we mentioned, there are some wonderful lye calculators online that will do the math for you. Our favorite is on

Apricot Kernel Oil

SAP VALUE: 0.139
Good for: Highly Conditioning, Moisturizing, Stable Creamy Lather 

Apricot kernel oil is a golden cold-pressed carrier oil that has a light, nutty scent. It is high in oleic and linoleic acids, and vitamins A, E, and C, making it very moisturizing and conditioning to the skin. In soapmaking, it is important to keep apricot kernel oil to 10 percent or less or it will make soap too soft.

Argan Oil

SAP VALUE: 0.136
Good for: Moisturizing, Conditioning, Adding Hardness, Stable Rich Lather 

Argan oil is cold-pressed from the kernel of the Moroccan argan tree. It is a lightweight golden oil that that is high in antioxidants and vitamins A and E. It is a more expensive oil, but the properties make this a great soap for aging skin.

For more information:


Avocado Oil

SAP VALUE: 0.133
Good for: Medium Creamy Lather, Conditioning 

Avocado oil has a light yellow-green tint and is slightly thicker than many carrier oils. It is high in vitamins A, B, D, and E as well as oleic and palmitoleic acids and is considered a healing and moisturizing oil for dry and mature skin.


Babassu Oil

SAP VALUE: 0.175
Good for: High Lather, Cleansing, Adding Hardness 

Babassu is a great substitute for coconut oil for those with coconut allergies. Its cleansing ability in soap is high, and it’s gentler than coconut oil. It is rich in vitamin E, phytosterols, and other antioxidants. Babassu also speeds soap to trace.

For more information:



SAP VALUE: 0.067 
Good for: Adding Hardness 

Beeswax is primarily used to harden soap bars when other oils that are desired may leave the soap softer than preferred. Also, it does not fully saponify, leaving properties in the soap to help naturally moisturize the skin and maintain that moisture for dry or itchy skin. It’s a great addition for those with sensitive skin.

Castor Oil

SAP VALUE: 0.128 
Good for: High Stable Bubbles, Creamy Lather, Moisturizing, Conditioning 

Castor oil is a thick, yellow oil cold-pressed from beans from the castor bush. It is about 90 percent ricinoleic acid, a fatty acid that is traditionally used to treat skin rashes and infections. Combined with honey, castor oil gives an amazing lather, which is why we like to use it in shampoo bars. Castor oil also helps speed soap to trace.


Cocoa Butter

SAP VALUE: 0.138 
Good for: Stable Lather, Hard Bar, Conditioning, Moisturizing 

Cocoa butter is made from the roasted seeds of the cacao tree. Like many other carrier oils and butters, it is high in vitamin E and other antioxidants. If it is pure, it has a cocoa scent and is hard, not creamy, when at room temperature. Cocoa butter makes a hard soap bar and is an excellent moisturizer. Like beeswax, it doesn’t fully saponify and has properties that help hold moisture in the skin.


Coconut Oil

SAP VALUE: 0.183
Good for: High Lather, High Bubbles, Cleansing, Hard Bar

Coconut oil is a great ingredient to create a hard, bubbly, cleansing soap bar. Solid at temperatures below 76°F, nondeodorized coconut oil has a strong coconut scent that only slightly remains in unscented soap. It can be drying to the skin if used in excess of 45 percent of the oils in the recipe, with the exception of salt soaps, due to high superfatting.


Grapeseed Oil

SAP VALUE: 0.130 
Good for: Medium Creamy, Stable Lather, High Conditioning 

Grapeseed oil is a lightweight, greenish-yellow oil that is high in linoleic acid, omega-6 fatty acids, and antioxidants. As a mild astringent, it’s great for acne. Grapeseed oil creates a creamy lather and is highly conditioning to the skin and hair.

Hazelnut Oil

SAP VALUE: 0.136 
Good for: Stable Medium Lather, Moisturizing, Cleansing 

Hazelnut oil is a light, amber-colored oil with a nutty scent when unrefined. It is an all-around great oil for soapmaking because it creates a stable lather with medium-size bubbles. It is also cleansing and moisturizing. It slightly slows soap coming to trace and makes a softer soap unless used in low amounts. Hazelnut oil is high in oleic acid, vitamins, and minerals.

Hemp Seed Oil

SAP VALUE: 0.138 
Good for: Medium/Low Lather, High Conditioning 

Hemp seed oil makes a silky-feeling bar that has a good lather and is highly conditioning. It is high in vitamins A and E but does not last as long as other oils in soap before oxidizing. Plan to use your soap within 6 months rather than storing it for a long period, or use a lower superfat percentage like 5 percent if you add hemp seed oil to your recipe.

Jojoba Oil

SAP VALUE: 0.069 
Good for: Stable Strong Lather, Conditioning 

Jojoba oil is actually a wax cold-pressed from the beans of the jojoba shrub. It is very stable liquid, making it a great oil in long-term soaps and extracts. It creates a beautiful, strong lather and is conditioning to skin and hair. It does not fully saponify, creating a hydrating barrier to protect and moisturize. Jojoba can actually destroy lather when used in high amounts. I keep it below 15 percent of oils in recipes.



SAP VALUE: 0.141 
Good for: Stable Creamy Lather, Conditioning, Hard Bar 

Lard is the rendered fat from a pig. It makes a wonderfully hard and long-lasting bar with a stable, creamy lather. It also helps soap come to trace faster. Always choose lard from a free-range, natural source. You can find it at a health food grocery store and render it yourself by cooking it down and straining.

Macadamia Nut Oil

SAP VALUE: 0.139 
Good for: Conditioning, Hard Bar, Creamy Lather 

Macadamia nut oil closely resembles sebum, the oil our skin naturally produces, making it great for all skin types. It is a light oil with a slight nutty scent. It is high in antioxidants and is composed of almost 60 percent oleic acid, with omega-3 and omega-6 fatty acids. This makes it a great ingredient for creating a nourishing soap bar.


Mango Butter

SAP VALUE: 0.145 
Good for: Conditioning, Moisturizing, Hard Bar, Creamy Lather 

Mango butter is similar to shea butter in hardness and texture. Like many natural oils, it is high in vitamins A and C as well as antioxidants. It’s great for those with dry skin, especially for use in facial soaps thanks to its high moisturizing ability. It helps create a hard bar with a stable creamy lather.


Neem Oil

SAP VALUE: 0.139 
Good for: Stable Creamy Lather, Conditioning, Moisturizing, Hard Bar 

Neem has traditionally been used as an antibacterial and anti-inflammatory agent. It is very calming to the skin, making it a great ingredient in soap for those with acne or sensitive skin. It creates a stable, creamy lather in a hard, long-lasting bar.

Olive Oil

SAP VALUE: 0.135 
Good for: Low Cleansing, Very Conditioning 

Olive oil makes a very gentle soap for babies, people older than 70, and anyone with skin conditions requiring a gentle soap because it is so low in cleansing power. It is high in antioxidants like vitamin E and polyphenols. It makes a softer bar, but hardening and cleansing oils like coconut can be added to increase hardness.

Shea Butter

SAP VALUE: 0.128 
Good for: Stable Lather, Conditioning, Hard Bar 

Shea butter is a creamy, soft butter that gives a silky feeling to soap bars. It is high in vitamins A and E as well as fatty acids and minerals. It doesn’t fully saponify, making it a great ingredient to increase the nourishing properties of soap.


Sweet Almond Oil

SAP VALUE: 0.139 
Good for: Stable Medium Lather 

Usually added to soap recipes for its moisturizing effects on hair and skin, sweet almond oil also creates a mild soap with a stable medium lather that is great for those with sensitive skin. It contains vitamins A and E and linoleic acid, and is high in oleic acid-a moisturizing fatty acid.



SAP VALUE: 0.143 
Good for: Stable Creamy Lather, Conditioning, Slightly Cleansing, Hard Bar 

Tallow is the number one traditional ingredient for soapmaking. It makes a fabulous hard, bubbly, conditioning and cleansing bar of soap. Remove the superfat content and you have a great laundry bar. Choose grass-fed, organic sources in health food grocery stores or local farms.


A Note on Nut Allergies

Nut allergies are a serious concern. I make soaps for people in my family who cannot have nuts, so I’ve developed and included in this book some recipes with no-nut oils or nut butters.

If you have a tree-nut allergy, watch out for coconut oil, sweet almond oil, hazelnut oil, and macadamia nut oil. Replacing coconut oil in soaps can be difficult, but ethically sourced palm oil or babassu oil makes a good substitute. Check the recipe labels to quickly identify nut-free recipes.

Sources / References

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Kelly Cable

  • The Natural Soapmaking Book For Beginners
  • DIY Soaps: Using All-Natural Herbs, Spices & Essential Oils

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