Reconstitution Calculator
Calculate peptide concentration, dosing volume, and syringe units.
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Syringe Diagram
How the peptide calculator works
Reconstitution is arithmetic, not chemistry. A lyophilised vial holds a known mass of peptide; adding bacteriostatic water dissolves it into a known volume. The concentration is the first divided by the second, and everything else follows from it. This calculator runs those steps and converts the result into insulin syringe units so the figure can be read straight off a U-100 barrel.
concentration (mg/ml) = peptide mass (mg) ÷ water volume (ml)
volume (ml) = target quantity (mg) ÷ concentration (mg/ml)
syringe units = volume (ml) × 100 (U-100)
Worked example: a 10mg vial reconstituted with 2ml of bacteriostatic water gives 5mg/ml. A researcher working to 0.5mg draws 0.1ml, which is 10 units on a U-100 insulin syringe. Reconstitute the same vial with 1ml instead and the concentration doubles to 10mg/ml, halving the draw to 5 units. Neither is more correct — the volume you choose is a working preference, and the only real mistake is failing to record it.
Concentration by vial size and water volume
Every figure below is the vial mass divided by the water volume, in mg/ml. It is a conversion reference for the vial sizes stocked here, not a recommendation of how much water to use or how much solution to draw.
| Vial content | + 1ml BAC | + 2ml BAC | + 3ml BAC |
|---|---|---|---|
| 2mg | 2.00 mg/ml | 1.00 mg/ml | 0.67 mg/ml |
| 5mg | 5.00 mg/ml | 2.50 mg/ml | 1.67 mg/ml |
| 10mg | 10.00 mg/ml | 5.00 mg/ml | 3.33 mg/ml |
| 15mg | 15.00 mg/ml | 7.50 mg/ml | 5.00 mg/ml |
| 20mg | 20.00 mg/ml | 10.00 mg/ml | 6.67 mg/ml |
| 30mg | 30.00 mg/ml | 15.00 mg/ml | 10.00 mg/ml |
Peptide calculator FAQs
How does a peptide calculator work?
It is a unit conversion. Reconstituting a lyophilised vial with bacteriostatic water gives a solution whose concentration is simply the peptide mass divided by the water volume. A 5mg vial reconstituted with 2ml of bacteriostatic water yields 2.5mg/ml. Once you know the concentration, the volume containing any given quantity is that quantity divided by the concentration. The calculator does both steps and converts the result into insulin syringe units.
What is the formula for peptide reconstitution?
Concentration (mg/ml) = peptide mass (mg) ÷ bacteriostatic water volume (ml). Volume to draw (ml) = target quantity (mg) ÷ concentration (mg/ml). On a U-100 insulin syringe, 1ml equals 100 units, so units = volume in ml × 100. Every figure this calculator produces comes from those three lines.
How much bacteriostatic water should I add to a vial?
There is no single correct volume — it is a working preference, not a property of the peptide. More water gives a lower concentration and a larger, easier-to-measure draw volume; less water gives a higher concentration and a smaller draw. Most researchers pick a volume that puts their working quantity somewhere in the middle of the syringe barrel, since both extremes lose precision. Whatever you choose, record it against the batch, because the concentration is meaningless without it.
Can I use this calculator for BPC-157, TB-500 or GHK-Cu?
Yes. The arithmetic is identical for every lyophilised peptide — only the vial mass changes, which you enter yourself. Select or type the milligram content printed on your vial, set the water volume, and the calculator returns the concentration and the volume containing whatever quantity you specify. It does not suggest what that quantity should be for any compound.
Does it work for blends like BPC-157 + TB-500 or CJC-1295 + Ipamorelin?
It works, with one caveat worth understanding. Enter the total peptide mass in the vial and the calculator returns the total concentration. In a blend each component sits at its own concentration — a 5mg + 5mg vial in 2ml is 5mg/ml total but 2.5mg/ml of each component. Any volume you draw contains both in the ratio the vial was filled at, so treat the per-component figure as the meaningful one.
How do I convert millilitres to insulin syringe units?
On a U-100 syringe, 100 units is 1ml, so multiply millilitres by 100. 0.25ml is 25 units, 0.1ml is 10 units. U-100 is the standard marking on 0.3ml, 0.5ml and 1ml insulin syringes sold in the UK, and this calculator assumes it. Check your syringe barrel before relying on the conversion, because U-40 syringes also exist and are marked differently.
Why does the calculator say the volume exceeds my syringe?
Because the concentration is too low for the quantity you entered — the volume needed will not fit in the barrel. Either use less bacteriostatic water when reconstituting, which raises the concentration and shrinks the draw, or use a larger syringe. Splitting a single draw across two injections is the other option but introduces measurement error twice.
Is bacteriostatic water the same as sterile water?
No. Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits microbial growth and allows a vial to be entered more than once. Sterile water has no preservative, so a vial reconstituted with it is single-use in practice. For any peptide a researcher expects to draw from repeatedly, bacteriostatic water is the normal choice.
How long does a reconstituted peptide last?
Reconstituted solution is held at 2-8°C and is considerably less stable than the lyophilised powder, which keeps at -20°C for far longer. Aliquoting immediately after reconstitution and freezing single-use portions avoids repeatedly re-entering one vial, which is the main practical cause of degradation. Check the certificate of analysis and storage guidance for the specific compound.
Is this peptide calculator free?
Yes, it is free and needs no account. It runs entirely in your browser, so nothing you enter is transmitted or stored. It is provided for laboratory research use only.
This calculator is for research purposes only. Not for human consumption.