Work out preservative dose for cosmetics instantly with clear inputs, formula shown and shareable results.
Preservative dose is the supplier's recommended use level capped at the regulatory maximum for the ingredient. Any product containing water needs preservation; truly anhydrous products generally do not. The dose must be justified by challenge testing, not by the label recommendation alone.
Preservative dose
Preservative (g) = batch size x min(recommended use %, regulatory maximum %) / 100
Preservative use levels are legally capped and preservative efficacy must be demonstrated by challenge testing under cosmetic safety regulation.
Whenever water is present and the product will be exposed to contamination in use. Anhydrous oils, balms and waxes usually do not need one, but any water ingress changes that.
Deliberately inoculating the product with specified organisms and monitoring their reduction over time. It is the only evidence that a preservative system actually works in that formula.