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

The Four Properties to Balance

Every oil contributes differently to these four qualities:

• Hardness — how firm the bar is, and how long it lasts in the shower
• Cleansing — how well the soap removes dirt and oil
• Lather — both fluffy/bubbly lather and creamy lather are valuable, but different oils produce different types
• Conditioning — how moisturizing and skin-friendly the finished bar is

A good recipe balances these. A high-coconut soap cleans well and lathers big, but can be drying. A high-olive soap is gentle and conditioning, but takes months to cure and produces a quieter lather. Most recipes balance 2–4 oils to hit all four targets.

Coconut Oil

Best for: Hardness, cleansing, fluffy lather
Typical usage: 20–30% of recipe

Coconut oil is the workhorse of soap making. It produces a rock-hard bar that pops out of the mold quickly, creates dramatic, bubbly lather, and cleans extremely well. The downside: at high percentages (above 30–35%), it can be drying and strip skin's natural oils. Most recipes use 20–30% and keep superfat at 5–8% to counteract this. If you're making a castile-style bar, you can skip coconut entirely.

Olive Oil

Best for: Conditioning, skin-loving bars, long shelf life
Typical usage: 40–100% of recipe

Olive oil produces a classic, conditioning soap that's gentle on sensitive skin. A 100% olive oil soap (called Castile) is one of the mildest you can make — but it requires a 6–12 month cure to harden properly and produces a dense, creamy rather than fluffy lather. Most beginners use 40–70% olive blended with harder oils. Use pomace or regular olive oil (not extra virgin, which can cause discoloration).

Castor Oil

Best for: Lather booster, creaminess
Typical usage: 5–10% of recipe

Castor oil's superpower is lather enhancement — even small amounts (5%) noticeably improve bubble quality and creaminess. Above 10%, bars can become soft and tacky. Almost every recipe benefits from a small castor addition. It also helps bind fragrance oils in your recipe.

Palm Oil

Best for: Hardness, stable lather
Typical usage: 20–30% of recipe

Palm oil hardens bars similarly to coconut but is less cleansing and more conditioning. It creates a stable, creamy lather. Many soap makers are moving away from palm due to sustainability concerns — good substitutes include lard, tallow, or a blend of shea butter and coconut. If you use palm, look for RSPO-certified sources.

Shea Butter

Best for: Skin conditioning, creamy lather
Typical usage: 5–15% of recipe

Shea butter adds a silky, skin-softening quality to finished bars. It contributes to hardness as a solid fat, but at high percentages can make bars feel waxy or slow to lather. At 5–15%, it adds a noticeable luxury feel without downsides. It's also a good palm substitute in smaller amounts.

Sweet Almond Oil

Best for: Skin conditioning, mild cleansing
Typical usage: 10–20% of recipe

Sweet almond is a lightweight conditioning oil that absorbs well and contributes to a creamy, moisturizing bar. It has a shorter shelf life than olive, so soaps with a high sweet almond content should be used within 6–12 months. A good choice for facial bars and baby soap recipes.

Building Your First Recipe

A well-balanced starting point for beginners:

• 30% Coconut Oil — hardness + lather
• 40% Olive Oil — conditioning + longevity
• 20% Palm or Lard — hardness + stable lather
• 10% Castor Oil — lather boost

Once you've got your percentages, use our Lye Calculator to convert them into exact NaOH and water amounts for your batch size. Adjust superfat between 5–8% based on how moisturizing you want the bar.