What a SAP value represents
A SAP value expresses how much alkali is needed to saponify a given weight of an oil or fat. NaOH and KOH values differ because the alkalis have different molecular weights.
Why values can vary
Natural materials vary by cultivar, processing, refining, and supplier specification. Calculator databases are formulation tools, not a replacement for checking technical documents when precision is critical.
Oil properties are multi-dimensional
Lauric and myristic acids often increase cleansing and fast lather, while palmitic and stearic acids support hardness and creamy lather. Oleic, linoleic, linolenic, and ricinoleic profiles influence conditioning, solubility, lather, and shelf stability.
Substitution requires recalculation
Replacing one oil with another changes the lye requirement and the expected performance. Never substitute solely by weight without recalculating the complete recipe.