Peptide Reconstitution Calculator

For a 5 mg BPC-157 vial, 2 mL of bacteriostatic water is the most common mix. That gives 2,500 mcg per mL, so a 250 mcg dose is 10 units on a 100-unit insulin syringe — an easy whole number to read. If you prefer 1 mL of water, the same 250 mcg dose becomes 5 units, which is harder to measure accurately. The amount of water never changes how much peptide you get; it only changes the concentration and therefore how many units you draw.

A 100-unit (1 mL) insulin syringe with a 29-31 gauge, 8 mm needle is the standard choice for subcutaneous peptide injections. The fine graduations let you measure small volumes precisely. Use a 1 mL syringe when you want to read in millilitres, and a 3 mL syringe only for larger-volume intramuscular oil injections — it is far too coarse for microgram peptide dosing.

No. The vial contains a fixed amount of peptide. Adding more water dilutes it, so each unit drawn contains less peptide, but you simply draw more units for the same dose. Choose the water volume that puts your usual dose on a clean, readable mark on your syringe.

Concentration (mcg/mL) = vial strength in mcg ÷ millilitres of water added. Draw volume (mL) = dose in mcg ÷ concentration. Units = draw volume × 100. Example: a 10 mg vial with 2 mL of water is 5,000 mcg/mL; a 500 mcg dose is 0.1 mL, or 10 units.

Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacterial growth and lets a reconstituted vial be used across multiple draws. Sterile water has no preservative and is generally intended for single use. For multi-dose peptide vials, bacteriostatic water is the usual choice.

Most reconstituted research peptides are kept refrigerated at 2-8 °C and used within roughly 4 weeks, though stability varies by peptide. Keep the vial away from light, avoid freeze-thaw cycles, and swab the stopper with alcohol before every draw.

Swab both stoppers with alcohol, then let the bacteriostatic water run slowly down the inside wall of the vial rather than spraying it directly onto the powder. Swirl gently or leave it to dissolve on its own. Never shake the vial — vigorous agitation can denature the peptide.

Doses per vial = total vial strength ÷ dose per injection. A 10 mg vial dosed at 500 mcg gives 20 doses regardless of how much water you add. The calculator above shows this alongside your draw volume so you can plan how long a vial lasts.