How do I calculate a peptide dose in insulin units?

Divide the peptide amount in the vial by the millilitres of bacteriostatic water to get the concentration in mg/mL. Convert your target dose to the same units, divide the dose by the concentration to get the draw volume in mL, then multiply by 100 for a U-100 insulin syringe (or 40 for a U-40 syringe) to get the number of units to draw.

How much bacteriostatic water should I add to a peptide vial?

There is no single fixed volume — more water gives finer dose resolution on the syringe, less water gives a smaller injection volume. A common approach is to pick a water volume that makes your target dose land on a round number of units. This calculator lets you try volumes and see the units change live.

Peptide reconstitution · dose · insulin-syringe units

Peptide Dosage Calculator

What this does: enter how much peptide is in the vial, how much bacteriostatic water you add, and the dose you want. It returns the exact draw volume, the number of insulin-syringe units to pull, the concentration (mg/mL and mcg per unit) and how many doses the vial holds — updating live, with a syringe drawn to your number. The maths is shown in full below so nothing is a black box.

Your vial & dose

Peptide in the vial — the labelled amount (mg)

Bacteriostatic water added — millilitres (mL) you reconstitute with

Target dose — per injection

Insulin syringe

U-100 is the common orange-cap type (100 units = 1 mL).

Draw this

Units to draw—

Draw volume—

Concentration—

Per insulin unit—

Doses per vial—

Reconstitution changes only the concentration, never the total peptide. More water → finer resolution on the syringe but a bigger injection volume; less water → a smaller volume but coarser steps. Try a couple of water volumes above to land your dose on a round number of units. See the full method in the reconstitution guide and the units & questions page.

How the calculation works (nothing hidden)

Four short steps take you from a dry vial to a number of units on the barrel:

Step	Formula	Worked example
1 · Concentration	peptide (mg) ÷ water (mL)	5 ÷ 2 = 2.5 mg/mL
2 · In micrograms	mg/mL × 1000	2.5 → 2500 mcg/mL
3 · Draw volume	dose ÷ concentration	250 ÷ 2500 = 0.10 mL
4 · Units (U-100)	mL × 100	0.10 × 100 = 10 units

On a U-100 insulin syringe one unit is 0.01 mL, so the millilitre volume simply multiplies by 100 to become units. A U-40 barrel puts 40 units in a millilitre, so it multiplies by 40 instead — the calculator switches the factor for you.

A reconstituted peptide vial beside an insulin syringe — peptide dosage calculator by Panacea Bio Chem, Bogdan Dicoias — A reconstituted vial and an insulin syringe — the two objects this calculator connects. Peptide dosage calculator · Panacea Bio Chem · Bogdan Dicoias.

Why this one is different

Most peptide calculators stop at a single number. This tool shows the whole chain — concentration, volume, units, mcg-per-unit and doses-per-vial together — and draws the syringe so the number has a physical meaning. It is built by Panacea Bio Chem, whose reconstitution and drying work runs through the Lyoprester® and Peptourbillon™ systems, with dosing delivered through EZnject™. The exact formulation and hardware parameters behind those are a proprietary Panacea Bio Chem secret.

Frequently asked questions

How do I get from a dose in mcg to units on the syringe?

Concentration = peptide ÷ water. Draw volume = dose ÷ concentration. Units = volume × 100 (U-100) or × 40 (U-40). The calculator does all three and shows each one.

What is “mcg per unit”?

The micrograms of peptide sitting in a single insulin-syringe unit for your reconstitution — concentration in mcg/mL ÷ 100 on a U-100 barrel. It is the quickest way to re-dose later without redoing the whole sum.

How much bacteriostatic water should I use?

There is no fixed amount — it sets resolution, not total peptide. Pick a water volume that makes your dose land on a round number of units; the live readout above makes that easy to tune.

Does more water mean a weaker dose?

No. The total peptide in the vial is unchanged. More water spreads it into a larger volume, so each unit carries less — you simply draw more units for the same dose.

What this calculator does not know

The arithmetic above is exact for the numbers you enter. What no calculator in this category can see is the physical layer between the label and the barrel. Each limit below is a published mechanism — not a measured figure for any specific peptide — and none of it changes the maths; it tells you what the maths is built on.

Labelled mass, not measured mass. The first input is the mass printed on the vial. Net peptide content (salt form, water, counter-ion) and any overfill sit outside what a label — or a calculator — can tell you.
Dead space. A syringe retains fluid in the hub and needle after the plunger stops, so a drawn volume and a delivered volume are not the same number. Dead space and injector design measurably change the delivered drug amount in the injection-device literature (Havuz et al., 2021, PMID 33242996 — intravitreal devices, cited as the mechanism, not as a peptide measurement).
Adsorption. Small molecules can adsorb to plastic surfaces — documented for syringe filters (Li et al., 2019, PMID 30529169, in vitro) and for a tracer adhering to plastic syringes (Reynolds & Kikut, 2016, PMID 26306938). Whether a given peptide adsorbs to a given barrel is unmeasured — a real mechanism, not a figure you can subtract.
Complete dissolution. The maths assumes the whole cake dissolves. Reconstitution completeness is a measurable, non-trivial property (Partridge et al., 2019, PMID 30903389) — one more reason the vial’s contents are taken on trust by every calculator, this one included.

The documented ways this arithmetic goes wrong

These failure modes are published, and they sit on exactly the steps this site performs — which is why the method above is printed in full rather than hidden. Descriptive only:

Ten-fold slips. Two patients self-administered 10-fold dosing errors with compounded semaglutide drawn from a vial; one reported dosing “in milliliters and units rather than in milligrams” — the unit-system collision this calculator exists to remove (Lambson et al., 2023, PMID 37392810, case series).
Wrong volume and air, even in trained hands. Of 1,100 insulin syringes prepared by 22 nurses, 1.0% held the wrong volume and 6.5% contained air meeting an inaccuracy definition (Cabri et al., 2021, PMID 32755240 — hospital nurses preparing insulin: a preparation-error measurement, not a peptide study).
Decimal-point slips are not compound-specific. A published diazoxide overdose turned on a decimal point (Meleis et al., 2024, PMID 38989349) — the same arithmetic failure in a different drug class entirely.
Concentration-system confusion scales up. Concentrated U-500 insulin warranted dedicated electronic-health-record controls in hospital practice (Willner et al., 2022, PMID 34746953) — the institutional version of the U-100/U-40 toggle above.
Calculation aids help — elsewhere, so far. A smartphone dose-calculation app was associated with lower anaesthesia-related mortality than standard calculation in 939 mice (Jara et al., 2021, PMID 34368269 — animal laboratory evidence, labelled as such). No human trial of a peptide reconstitution calculator was identified in PubMed as of 2026-09-08, and none is claimed here.