Peptide Reconstitution Chart
A plain lookup table: how common vial sizes and bacteriostatic water volumes combine into a concentration, and what that concentration means on a standard insulin syringe. One formula does all of it, and it is written out below so you are not trusting a black box.
Reviewed by the PepGuard team · Last reviewed Jul 28, 2026
- Concentration (mg/mL) = vial milligrams ÷ bacteriostatic water millilitres. Everything else follows from that.
- On a U-100 insulin syringe, 1 unit = 0.01 mL, so 1 unit delivers (concentration × 10) micrograms.
- Bacteriostatic water is sterile water with 0.9% benzyl alcohol — it is not for use in neonates, and a punctured vial should be dated and discarded within 28 days (CDC).
- This chart is arithmetic. Whether a given compound has a dose worth measuring is a separate question, answered on that compound's own report.
Photo: CDC / UnsplashThe one formula behind every reconstitution chart.
Every peptide reconstitution chart, calculator, and “cheat sheet” is these three lines:
- Concentration (mg/mL) = milligrams of peptide in the vial ÷ millilitres of bacteriostatic water you add.
- Draw volume (mL) = your target dose (in mg) ÷ that concentration.
- Syringe units = draw volume (mL) × 100, on a standard U-100 insulin syringe where 1 mL is marked as 100 units.
The concentration step is the only one that involves the vial. The other two are just unit conversions. A “chart” is this formula pre-computed for round numbers; the reconstitution calculator is the same formula run on the exact numbers you type in.
Vial concentration ÷ desired dose = how much to draw into the syringe. That’s the whole calculation, the calculator below just does the arithmetic for you.
Vial size + bacteriostatic water → concentration.
Each cell is the resulting concentration in mg/mL. Read down to your vial size, across to the water volume you plan to add.
| Vial size | + 1 mL water | + 2 mL water | + 3 mL water | + 5 mL water |
|---|---|---|---|---|
| 2 mg | 2.0 mg/mL | 1.0 mg/mL | 0.67 mg/mL | 0.4 mg/mL |
| 5 mg | 5.0 mg/mL | 2.5 mg/mL | 1.67 mg/mL | 1.0 mg/mL |
| 10 mg | 10.0 mg/mL | 5.0 mg/mL | 3.33 mg/mL | 2.0 mg/mL |
| 15 mg | 15.0 mg/mL | 7.5 mg/mL | 5.0 mg/mL | 3.0 mg/mL |
| 20 mg | 20.0 mg/mL | 10.0 mg/mL | 6.67 mg/mL | 4.0 mg/mL |
| 30 mg | 30.0 mg/mL | 15.0 mg/mL | 10.0 mg/mL | 6.0 mg/mL |
What one insulin-syringe unit delivers, by concentration.
On a U-100 syringe, 1 unit is 0.01 mL. So the peptide in one unit is the concentration × 10, in micrograms.
| Concentration | 1 unit (0.01 mL) delivers | 10 units deliver | Units for a 250 mcg dose |
|---|---|---|---|
| 0.4 mg/mL | 4 mcg | 40 mcg | 62.5 units |
| 1.0 mg/mL | 10 mcg | 100 mcg | 25 units |
| 2.0 mg/mL | 20 mcg | 200 mcg | 12.5 units |
| 2.5 mg/mL | 25 mcg | 250 mcg | 10 units |
| 5.0 mg/mL | 50 mcg | 500 mcg | 5 units |
| 10.0 mg/mL | 100 mcg | 1 mg | 2.5 units |
| 15.0 mg/mL | 150 mcg | 1.5 mg | 1.7 units |
Worked example: a 5 mg vial reconstituted with 2 mL of bacteriostatic water is 2.5 mg/mL (Chart 1). At 2.5 mg/mL, one syringe unit is 25 mcg, so a 250 mcg dose is 10 units (Chart 2). Change the water to 1 mL and the same vial is 5 mg/mL, one unit is 50 mcg, and the same dose is 5 units.
Bacteriostatic water: what it is, and the parts with an actual source.
Bacteriostatic Water for Injection, USP is sterile water with 0.9% benzyl alcohol added as a preservative. The benzyl alcohol inhibits bacterial growth, which is what lets a single vial be punctured and drawn from repeatedly instead of once. Its FDA-approved labelling is narrow: it is “indicated only for diluting or dissolving drugs for intravenous, intramuscular or subcutaneous injection, according to instructions of the manufacturer of the drug to be administered.”
Two specifics from that label are worth stating plainly. First, it is marked “NOT FOR USE IN NEONATES” — benzyl alcohol is toxic to newborns. Second, the label notes that animal studies estimate an intravenous dose of up to about 30 mL of the 0.9% solution can be given to an adult without toxic effects — a reminder that the diluent itself is not inert at volume.
For storage after you reconstitute: the CDC’s injection-safety guidance is to date a multi-dose vial the moment it is first punctured and discard it within 28 days, unless the manufacturer specifies a different period, and never past the printed expiry. That 28-day figure is about the preservative and sterile-handling window; it is not a promise about the peptide itself, whose stability depends on the specific compound and whether it is kept refrigerated.
A chart is not a protocol.
Everything above tells you how to turn a vial into a concentration and a concentration into syringe units. None of it tells you whether a given compound has a dose worth measuring, what that dose is, whether it is legal to obtain, or whether it has ever been tested in a person. That is the part a chart cannot do, and it is the part that actually matters.
Before using any of this, read the evidence report for the specific compound. Each one covers what dose (if any) is supported by real data, the regulatory status, and the reported side effects, each traced to a primary source:
The storage and safety claims, traced back.
The arithmetic needs no citation. The diluent, storage, and syringe-standard claims do, and here they are.
Reconstitution-chart questions, answered.
It is a lookup table. One axis is the amount of peptide in the vial (in milligrams), the other is how much bacteriostatic water you add (in millilitres), and each cell is the resulting concentration in mg/mL. A second table then converts that concentration into how much peptide sits in one unit on a standard U-100 insulin syringe. It saves you doing the arithmetic each time, but the arithmetic is all it is — a chart cannot tell you what dose is appropriate for any given compound.
Concentration (mg/mL) = milligrams of peptide in the vial ÷ millilitres of bacteriostatic water added. To find a draw volume: draw volume (mL) = your target dose (mg) ÷ that concentration. To convert to syringe units on a U-100 insulin syringe: units = draw volume (mL) × 100. That is the entire calculation; everything on a reconstitution chart is those three lines applied to common numbers.
It depends entirely on your concentration. If you reconstitute a 5 mg vial with 1 mL of bacteriostatic water, the concentration is 5 mg/mL, so one U-100 unit (0.01 mL) delivers 50 mcg, and a 250 mcg dose is 5 units. Add 2 mL of water to the same vial instead and the concentration is 2.5 mg/mL, one unit delivers 25 mcg, and the same 250 mcg dose is 10 units. The chart below shows the concentrations; the free calculator does the dose-to-units step for your exact numbers.
There is no single correct volume. More water makes a more dilute solution that is easier to measure in small increments but takes a larger injection volume; less water is more concentrated. A common goal is to pick a water volume that puts your typical dose somewhere between roughly 10 and 50 units on a U-100 syringe, because that is the range that is easiest to measure accurately. The chart below lets you see several options at once.
Bacteriostatic water contains 0.9% benzyl alcohol as a preservative, which is what allows a punctured vial to be used repeatedly rather than once. General injection-safety guidance from the CDC is to date a multi-dose vial when first punctured and discard it within 28 days unless the manufacturer specifies otherwise. Peptide stability itself varies by compound and by storage temperature, and is not something a generic chart can promise — check refrigeration guidance for the specific compound.
No. The reconstitution maths is identical for every peptide — milligrams in, millilitres of water, resulting concentration. What differs between compounds is what dose, if any, is supported by evidence, and that lives on each compound's own report, not on this chart.
Keep going.
This chart is the easy part.
Create your account to check any compound's evidence, dose support, and regulatory status before you reconstitute anything.