Determine the dosage of your peptides based on the amount of bacteriostatic water added to the vial — visualized on a U-100 insulin syringe. Educational tool for laboratory research only.
A research peptide is supplied lyophilized: freeze-dried into a fine powder at the bottom of the vial. In that state it is stable, but unusable in the laboratory — it has to be brought back into solution first. That step is called reconstitution: a measured volume of solvent, most often bacteriostatic water, is introduced into the vial and dissolves the powder.
The point that trips people up most often: the volume of water added never changes the amount of peptide in the vial. A 10 mg vial contains 10 mg whether you add 1 ml or 5 ml. What the volume changes is the concentration — and therefore how far up the syringe you have to draw to obtain a given amount. Add more water and the solution is more dilute, so the same quantity of peptide occupies more marks on the barrel.
Diluting more is not a loss: a lower concentration spreads the same content over more graduations, which makes small quantities easier to read on the barrel. This is the whole purpose of the calculator above — it converts, in real time, a quantity of peptide into a number of marks on a U-100 insulin syringe.
Everything rests on three relations. The calculator chains them together, but they are worth knowing so you can check a result by hand.
The last line is the one that causes the most confusion. On a U-100 insulin syringe, the graduations are not milliliters but insulin units: 100 IU = 1 ml, so 1 IU = 0.01 ml. A U-100 syringe labelled 0.5 ml therefore carries 50 marks, and one labelled 0.3 ml carries 30 — same scale, shorter barrel.
One last conversion is needed because quantities are often written in micrograms: 1 mg = 1 000 mcg. The calculator handles the unit switch on its own, which removes the most common source of error — a factor of a thousand.
Take the calculator's default values and follow the chain step by step.
Now change one single parameter: with 1 ml of water instead of 2, the concentration doubles to 10 mg/ml and those same 250 mcg fall on 2.5 IU — a mark that sits between two graduations and is much harder to read. Hence a practical rule: if the result lands under 5 IU, add more solvent.
Concentration obtained for the most common vial / solvent combinations, and the equivalent of one single syringe mark.
| Vial | Water added | Concentration | 1 IU equals |
|---|---|---|---|
| 2 mg | 1 ml | 2 mg/ml | 20 mcg |
| 2 mg | 2 ml | 1 mg/ml | 10 mcg |
| 5 mg | 1 ml | 5 mg/ml | 50 mcg |
| 5 mg | 2 ml | 2.5 mg/ml | 25 mcg |
| 5 mg | 3 ml | 1.67 mg/ml | 16.7 mcg |
| 10 mg | 1 ml | 10 mg/ml | 100 mcg |
| 10 mg | 2 ml | 5 mg/ml | 50 mcg |
| 10 mg | 3 ml | 3.33 mg/ml | 33.3 mcg |
| 10 mg | 5 ml | 2 mg/ml | 20 mcg |
| 15 mg | 3 ml | 5 mg/ml | 50 mcg |
| 20 mg | 2 ml | 10 mg/ml | 100 mcg |
| 30 mg | 3 ml | 10 mg/ml | 100 mcg |
Reading tip: the last column is the fastest shortcut. At 5 mg/ml, one mark equals 50 mcg — so 4 marks equal 200 mcg, no calculation needed.
It means bringing a lyophilized peptide — freeze-dried into powder form — back into solution by introducing a measured volume of solvent into the vial. The powder dissolves and yields a liquid whose concentration depends solely on the amount of peptide present and the volume added.
Bacteriostatic water contains roughly 0.9% benzyl alcohol, an agent that inhibits bacterial growth. It therefore allows a reconstituted solution to be kept for several weeks under refrigeration, whereas plain sterile water offers no such protection and is intended for a single use.
There is no single correct volume — only volumes that are more or less convenient to read. The usual approach is to pick a round concentration (1, 2, 5 or 10 mg/ml) so that one syringe mark corresponds to a whole number of micrograms. The calculator above shows the effect of the volume instantly, which is the quickest way to settle on one.
IU stands for international unit — the graduation scale used for insulin. On a U-100 syringe, 100 IU correspond to exactly 1 ml, so a single mark equals 0.01 ml. The unit measures a volume here, not a quantity of peptide: what a mark is worth in micrograms depends entirely on the concentration of the solution.
Two conversions cover everything: 1 mg = 1 000 mcg for quantities, and 1 ml = 100 IU on a U-100 syringe for volumes. The two scales only meet through the concentration, which is what links a quantity of peptide to a volume of liquid.
No. The vial contains what it contains, regardless of the solvent. Adding more water lowers the concentration, so the same quantity of peptide occupies a larger volume — and therefore more marks on the syringe. The total number of draws available from the vial does not change.
A solution reconstituted with bacteriostatic water keeps for 28 days refrigerated, at 2–8 °C, away from light and from repeated temperature swings. Past that point it is no longer considered reliable for research. Lyophilized powder, still sealed, is far more stable. Always refer to the documentation supplied with the batch.
The calculator flags it with an orange warning. Three options resolve it: pick a larger syringe, split the volume across several draws, or — the simplest — reconstitute with less solvent so as to raise the concentration. Changing the vial's water volume shifts every result at once.
Yes, because the arithmetic is identical whatever the molecule: it only handles quantities, volumes and concentrations. BPC-157, TB-500, GHK-Cu, GLP-Triple or kisspeptin all follow the same relations. Only the reconstitution and storage recommendations specific to each peptide differ.
Strictly educational content intended for research. These products are not intended for human consumption or for medical, diagnostic or therapeutic use. This tool does not constitute medical advice and does not suggest any human dosage — it only illustrates concentration calculations in a research context. Not for human consumption.