Reconstitution calculator
Work out how many units on an insulin syringe correspond to the dose you want. Enter the vial, the amount of solvent and the target dose.
This is a calculator, not advice. It does arithmetic only — it does not tell you whether to use anything, or at what dose. The prefilled numbers are a starting point taken from each entry, not a recommendation, and vial strengths differ between suppliers, so always work from the label on the vial you actually have. Many compounds here are not approved for human use. Getting milligrams, micrograms and IU mixed up is the documented way people are harmed with these — check the unit before you draw anything up. Nothing here is medical advice; talk to a doctor.
The arithmetic it does
Two steps, and the second is where nearly every mistake happens. First the concentration, which follows from the vial and the solvent you add:
concentration (mg/ml) = peptide (mg) ÷ volume added (ml)
Then the conversion to syringe markings. A U100 insulin syringe holds 100 units per millilitre, so one unit is 0.01 ml:
units = dose (mcg) ÷ concentration (mcg/ml) × 100
The trap is that 1 mg equals 1000 mcg. Dropping that factor of a thousand is the single most common reconstitution error, and it is silent — the number still looks plausible.
Worked example: a 10 mg vial with 2 ml of bacteriostatic water gives 5 mg/ml. A 250 mcg dose is 0.25 mg, which is 0.05 ml, which is 5 units on a U100 syringe.
Picking a compound loads three things from its entry: a typical vial size, a solvent volume, and — as the target dose — the conservative low end of that compound's documented range. All three are a starting point, not an instruction: vial sizes differ between suppliers, so change any of them to match the vial you actually have.
It also watches the concentration. Peptides do not always dissolve fully at very high concentrations, and a very dilute solution wastes peptide and needs an awkward volume — so if the mg/ml lands unusually high or low the calculator says so and nudges the solvent. Where a compound has a documented solubility limit the entry uses that figure; otherwise it applies a general guide, because peptide solubility varies and is rarely published — no per-compound number is invented to fill the gap.
And it works to a real vial. Set the vial size — 2, 3, 5 or 10 ml, with 3 ml as the standard default — and the rest follows it: the suggested solvent volume never exceeds the vial, the results show the total volume in the vial, and asking for more solvent than the vial holds is flagged.
One case the milligram field cannot handle: compounds dosed in International Units — insulin, hCG, the gonadotropins, growth hormone. IU measure biological activity, not mass, and do not convert to milligrams without the figure for your specific product. Units, IU and milligrams explains why, and the entries for those compounds carry the same warning. More on reconstitution and concentration.