Peptide tools and calculators that show their work.

Which one you want

Three questions come up constantly in laboratory solution preparation, and they need different arithmetic. The vial concentration calculator answers the common one: a vial holds a stated mass, a chosen volume of diluent goes in, and the result is the solution concentration in mg/mL with a per-graduation table for the record. The molarity calculator converts that mass concentration to a molar one, which is what any protocol expressed in µM or mM needs — and it is the place the salt-form problem bites, because the free-base molar mass and the mass actually in the vial are different numbers. The cost per milligram tool compares vial sizes on price per milligram rather than price per vial, which is the only comparison that means anything across different fills.

There used to be a separate concentration calculator page for each of the 66 compound families, all running the same arithmetic on a different label. The compound is an input, not a page, so it is a dropdown now — one calculator, prefilled with whichever vial sizes are actually stocked. Every tool prints its formula and its assumptions beside the result, because a number without its method cannot go into a laboratory record. None of them computes anything about administration.

Open the calculator on a compound

Each link opens the concentration calculator with that family's stocked vial sizes already loaded.