SAP Value of Oils for Natural Soap Making (Complete SAP Chart)

If you’ve ever run the same soap recipe through two different lye calculators and gotten slightly different results, you’re not imagining things.
It happens all the time.

One calculator might tell you to use 128 g of sodium hydroxide, while another suggests 131 g. That small difference can make soapmakers wonder which calculator is “right.” The answer is usually SAP values. Understanding what SAP values are — and why they vary — helps explain why soap calculators sometimes give different lye amounts.

If you’d like to go deeper into the science behind soapmaking, the Ultimate Natural Soap Making course inside Soapy Friends walks through the chemistry step by step.

What Is a SAP Value?

A saponification value (SAP value) is the number of milligrams of potassium hydroxide or sodium hydroxide required to saponify one gram of fat. Thank you, science, for measuring the molecular weight of oil samples for us.

In practical soapmaking terms, a SAP value tells us how much lye is needed to turn an oil into soap.

Different oils require different amounts of lye because they contain different fatty acid profiles. Oils with shorter fatty acid chains typically require more lye, while oils with longer chains require less.

For example:

• Coconut oil requires more lye
• Olive oil requires less
• Beeswax requires very little

That’s why lye calculators rely on SAP values to determine the correct lye amount for a recipe.

SAP Values Are Always Averages

Here’s the key thing to understand: SAP values are averages.
Yes, I said averages on purpose.

The SAP value charts used in lye calculators represent an average value measured across many samples of an oil. Because oils are natural agricultural products, their exact composition varies.

SAP values can change depending on:

• Season and climate
• Soil conditions
• Crop variety
• Growing region
• Method of extraction
• Refinement process

That means the olive oil sitting in your soap studio today is not chemically identical to the olive oil harvested next year. Fortunately, the variation is usually small enough that we can safely rely on the average SAP values used in soap calculators.

But it does mean that different calculators may use slightly different averages, which results in slightly different lye recommendations.

The SAP Values Used in Soapy Friends Calculations

For all of the soap recipes and worksheets I share at Soapy Friends, I use the SAP values from SoapMaker3 / SoapMaker Pro. Soap calculators are built using their own internal SAP value charts, so if you plug a recipe into another calculator and get slightly different lye numbers, that’s most likely why.

The difference is rarely large enough to affect a properly superfatted recipe, but it’s helpful to understand where those differences come from.

Converting Between NaOH and KOH SAP Values

SAP values can be expressed for either:

• NaOH (sodium hydroxide) – used for bar soap
• KOH (potassium hydroxide) – used for liquid soap

If you only have one SAP value, you can convert it.

NaOH → KOH
NaOH SAP value = KOH SAP value ÷ 1.4025

KOH → NaOH
KOH SAP value = NaOH SAP value × 1.4025

SAP Value Chart for Common Soapmaking Oils

The following SAP values are based on the SoapMaker Pro SAP value chart used in my formulations.

Oil	NaOH SAP	KOH SAP
Almond	0.136	0.191
Avocado	0.133	0.187
Babassu	0.175	0.245
Beeswax	0.067	0.094
Canola	0.133	0.187
Castor	0.128	0.180
Cocoa Butter	0.137	0.192
Coconut	0.180	0.252
Grapeseed	0.123	0.173
Hemp	0.137	0.192
Jojoba	0.069	0.097
Kokum Butter	0.135	0.189
Lard	0.138	0.194
Mango Butter	0.128	0.180
Neem	0.139	0.195
Olive	0.135	0.189
Palm	0.141	0.198
Palm Kernel	0.169	0.237
Rice Bran	0.128	0.180
Safflower (High Oleic)	0.135	0.189
Shea Butter	0.128	0.180
Sunflower (High Oleic)	0.135	0.189
Tallow	0.141	0.198

Why Learning SAP Values Still Matters

Even though most of us use soap calculators today, understanding SAP values is still valuable.

It helps you:

• Understand how lye calculations actually work
• Verify calculator results
• Recalculate older recipes
• Troubleshoot unusual formulation issues
• Design recipes manually if needed

And once you understand SAP values, the math behind soapmaking becomes much less mysterious.

SAP Values in Hard Oils vs Soft Oils

If you look closely at a SAP value chart, you’ll notice a pattern. Hard oils tend to have higher SAP values, while soft oils usually have lower SAP values. This comes down to their fatty acid structure.

Hard oils are typically rich in shorter, saturated fatty acids, which require more sodium hydroxide to saponify. Soft oils usually contain longer, unsaturated fatty acids, which require less lye.

Higher SAP values (more lye needed):

• Coconut oil
• Babassu oil
• Palm kernel oil

Lower SAP values (less lye needed):

• Olive oil
• Avocado oil
• Almond oil

Animal fats such as lard and tallow tend to fall somewhere in the middle because they contain a mix of saturated and unsaturated fatty acids. Understanding this pattern can make SAP values easier to remember when formulating recipes. If an oil is very hard and highly saturated, you can expect it to require more lye. If it’s a soft liquid oil rich in unsaturated fatty acids, it usually requires less.

Should You Worry About SAP Value Differences?

For most soapmakers, the answer is no. Because we formulate soap recipes with a superfat, small SAP value differences between calculators rarely cause problems.

For example, if one calculator differs by a gram or two of sodium hydroxide, that difference is usually well within the buffer created by your superfat.

Understanding SAP values simply helps you recognize that calculators aren’t giving random numbers — they’re just using slightly different averages. Understanding key points like this is one of the steps toward becoming a confident soap formulator!