Best Oils for Soap Making: What Each Oil Does and How Much to Use

The best oils for soap making are the ones that balance four things in the finished bar: hardness, cleansing, lather and conditioning. No single oil does all four well, so most recipes combine a hard fat (palm, lard, tallow or a butter), a cleansing oil (coconut), a gentle liquid oil (olive) and a few percent of castor oil for lather.

Once you know what job each oil does, reading or writing a recipe stops being guesswork. You can look at a formula like “olive 40, coconut 25, lard 30, castor 5” and predict roughly how the bar will feel before you make it.

Why oils behave differently: fatty acids in plain English

Every soaping oil is a mix of fatty acids, and each fatty acid becomes a slightly different soap. The oil’s personality comes from its mix.

Fatty acid	Found mostly in	What it contributes to the bar
Lauric and myristic	Coconut, babassu, palm kernel	Hardness, strong cleansing, big fluffy bubbles
Palmitic and stearic	Palm, tallow, lard, cocoa butter, shea	Hardness, long-lasting bar, stable creamy lather
Oleic	Olive, high-oleic sunflower, avocado, sweet almond, lard	Mildness, conditioning feel, slower to harden
Linoleic and linolenic	Sunflower, grapeseed, hemp, soybean, safflower	Silky feel, but more prone to rancidity and DOS
Ricinoleic	Castor	Boosts and stabilizes lather; sticky or soft in excess

A useful mental shortcut: saturated fats (lauric, myristic, palmitic, stearic) build hardness; unsaturated ones (oleic, linoleic, linolenic) build mildness and softness. The more unsaturated the oil, especially linoleic and linolenic, the shorter its shelf life. See soap shelf life and DOS.

Common soaping oils by role

Typical ranges are for bar soap made by cold process. They’re working ranges experienced makers stay within, not hard limits.

Oil or fat	Role	Typical % of oils	Notes
Olive oil	Conditioning base	25–100%	Mild, slow to trace, long cure at high %
Coconut oil (76°F)	Cleansing, bubbles, hardness	15–30%	Drying above about 30% in a normal bar
Babassu oil	Cleansing, bubbles	15–30%	Close substitute for coconut
Palm oil	Hardness, creamy lather	15–35%	Look for RSPO-certified sources
Lard	Hardness, creamy lather, mildness	25–70%	White, gentle bar; affordable
Tallow (beef or mutton)	Hardness, creamy lather	25–70%	Very hard, long-lasting bar
Shea butter	Hardness, silky feel	5–15%	Too much can reduce lather
Cocoa butter	Hardness	5–15%	Brittle above about 15%
Mango butter	Hardness, silky feel	5–15%	Similar role to shea
Castor oil	Lather booster	3–8%	Sticky, soft bars above about 10%
Sweet almond oil	Conditioning	5–15%	Higher in linoleic than olive
Avocado oil	Conditioning	5–20%	Rich feel; often unrefined and green
Rice bran oil	Conditioning, mild hardness	5–20%	Behaves like a lighter olive
High-oleic sunflower	Conditioning	5–20%	Cheaper olive substitute; check it’s high-oleic
Regular sunflower, grapeseed, hemp	Silky feel	Up to about 10–15%	High linoleic: DOS risk
Soybean oil	Conditioning	Up to about 15–20%	Inexpensive; shorter shelf life

For the lye math, every oil also has a SAP value. Look them up in the SAP value chart, but you rarely need to do it by hand; the lye calculator handles it.

Building a balanced recipe

A simple structure most recipes fit:

• Hard oils and butters: 30–50%. Palm, lard, tallow, shea, cocoa butter.
• Cleansing oils: 15–30%. Coconut or babassu.
• Soft, conditioning oils: 25–50%. Olive, rice bran, avocado, sweet almond.
• Lather booster: 3–8%. Castor oil.

Three starting points that fit that structure. Percentages only; run any of them through the lye calculator at your chosen superfat and batch size.

Style	Formula	What to expect
Classic three-oil	Olive 40%, coconut 30%, palm or lard 30%	Hard bar, good bubbles, beginner-friendly
Lard-based	Lard 60%, olive 15%, coconut 20%, castor 5%	Creamy, white, mild bar
Palm-free	Olive 35%, coconut 25%, shea 20%, cocoa butter 10%, castor 5%, avocado 5%	Firm, silky bar; slightly slower to unmold

Our three-oil beginner soap and palm-free soap follow the same structures as the first and third patterns, with full gram weights.

Single-oil soaps and what they teach

Making a bar from just one oil is a good way to understand what each oil does on its own.

• 100% olive (castile). Very mild, slippery lather, soft at first. Needs months of cure to become hard. See castile soap and curing soap.
• 100% coconut. Hard, very bubbly and strongly cleansing. Usually made with a high superfat, around 15–20%, to keep it from feeling drying. See 100% coconut oil soap.
• 100% lard or tallow. Hard, creamy and mild, with modest bubbles. See lard soap and tallow soap.

Most blended recipes exist because each of these extremes has a weakness the others cover.

Buying and storing soaping oils

• Buy fresh, from turnover-heavy sources. Old oils, especially high-linoleic ones, can already be on the way to rancid before they reach your pot.
• Check the type. “Coconut oil” for soap usually means 76°F (24°C) refined coconut; fractionated coconut oil is a different product and doesn’t soap the same. Sunflower comes in high-oleic and high-linoleic versions with different shelf lives.
• Store cool and dark. Keep liquid oils sealed, away from heat and light. Many makers add rosemary oleoresin extract (ROE) to fresh high-linoleic oils when they open them; follow the supplier’s rate.
• Smell before you soap. If an oil smells sharp, crayon-like or stale, don’t use it. Rancid oil makes a bar that smells off and is more likely to develop orange spots.
• Pomace olive oil is a lower grade that many soapers like because it traces faster than extra virgin. Either works.

Common mistakes

• Swapping oils without recalculating. Each oil needs a different amount of lye. Change an oil, rerun the calculator.
• Too much coconut. Above about 30% in an everyday bar, many people find it drying. If you want more bubbles, try castor or a little sugar instead. See soap additives.
• Too much castor. Above about 10%, bars get sticky and soft.
• Loading up on “luxury” liquid oils. Lots of avocado, almond, grapeseed and hemp sounds nice on a label but often makes a soft bar with a shorter shelf life.
• Confusing hard and brittle. Over 15% cocoa butter, or very high stearic recipes, can crack or crumble when cut.
• Ignoring trace speed. High-olive and high-liquid-oil recipes trace slowly; high-hard-oil recipes trace quickly, especially with warm temperatures.

Recipes by base oil

• Castile soap: olive on its own.
• Coconut oil soap: coconut-forward and bubbly.
• Tallow soap and lard soap: traditional hard fats.
• Shea butter soap and cocoa butter soap: butters in balance.
• Avocado oil soap and sweet almond oil soap: richer liquid oils.
• Ready to combine oils yourself? Make soap from scratch walks through designing and calculating your own recipe.