1. Separate supplied material from active matter
The surfactants aisle contains raw materials supplied at different active concentrations. Ten grams of one product is not automatically equivalent to ten grams of another. Record each supplier active fraction before you compare mildness, foam or total surfactant load.
2. A named surfactant still needs its own specification
SCI is a named surfactant, but its active contribution must come from the specification for the lot and grade you actually use. Do not copy a percentage from a blog and assume the supplied powder is mathematically identical to every other SCI grade.
3. Liquid amphoterics make the error easy to miss
Cocamidopropyl betaine is commonly supplied as a solution. The batch percentage therefore includes its carrier as well as surfactant solids. Entering the whole supplied percentage as active matter inflates the calculation and makes formula-to-formula comparisons misleading.
4. The useful calculator workflow
For each surfactant, multiply the formula percentage by the documented active fraction, then sum the active contributions. Keep the supplied percentages too: they still matter for water balance, processing and sensory work. The calculator is arithmetic; the supplier sheet is the source of the inputs.