Soap Making Oil Chart
Every oil needs a specific amount of lye to turn fully into soap, expressed as its SAP (saponification) value, and every oil also contributes different qualities to the finished bar. This chart lists both: approximate NaOH SAP values for cold and hot process soap, and what each oil actually does in a recipe.
How to read a SAP value
A SAP value is the grams of lye needed to saponify one gram of that oil. Olive oil's NaOH SAP value of roughly 0.134 means 100 grams of olive oil needs about 13.4 grams of sodium hydroxide for complete saponification, before any superfat discount is applied.
NaOH (sodium hydroxide) values are used for solid bar soap; KOH (potassium hydroxide) values are different and used for liquid soap. Never mix the two up, and never calculate a recipe by hand from a chart when a lye calculator will do it correctly in seconds, accounting for your full oil blend and chosen superfat percentage at once.
Hard oils: structure and lasting power
Coconut oil (SAP approx 0.183): produces big bubbly lather and a very hard bar, but is drying above roughly 30 percent of a recipe, which is why most bars keep it in the 15-30 percent range.
Palm oil (SAP approx 0.141): hardness and stable creamy lather, the traditional workhorse hard oil. Sustainably sourced palm or a tallow substitute matters to many makers.
Tallow (SAP approx 0.140) and lard (SAP approx 0.138): traditional animal fats giving hardness and a stable, creamy, low-bubble lather, popular in classic recipes and as palm alternatives.
Cocoa butter (SAP approx 0.137) and shea butter (SAP approx 0.128): hardness plus conditioning, usually used at 5-15 percent as a luxury addition rather than a base oil.
Soft oils: conditioning and mildness
Olive oil (SAP approx 0.134): extremely mild and conditioning, the sole oil in traditional castile soap. High percentages make a very gentle bar that is initially soft and benefits from a long cure.
Sweet almond oil (SAP approx 0.136) and sunflower oil (SAP approx 0.134): conditioning soft oils typically used at moderate percentages to add mildness without dominating the recipe.
Castor oil (SAP approx 0.128): the lather booster, used at just 5-10 percent to dramatically increase bubbles and lather stability. Above that it makes bars sticky and soft.
Balancing a recipe
A common beginner-friendly structure is roughly 30 percent hard oil for structure, 25 percent coconut for cleansing and bubbles, 40 percent olive or another soft oil for mildness, and 5 percent castor for lather, then run the whole blend through a lye calculator with a 5 percent superfat.
Lye calculators also report predicted bar qualities (hardness, cleansing, conditioning, bubbly, creamy) as numbers, which makes it easy to see whether a recipe is skewed before you ever mix it. Adjust the oil percentages until those numbers land in the recommended ranges the calculator shows.