Peptide Reconstitution Calculator

Units depend on your concentration. The formula is: draw volume (mL) = dose (mg) ÷ concentration (mg/mL), then multiply mL × 100 to convert to units on a 100-unit syringe. Example: 0.25 mg dose with a 2.5 mg/mL concentration = 0.1 mL = 10 units.

It depends on the concentration you want. Adding 1 mL to a 5 mg vial gives 5 mg/mL; adding 2 mL gives 2.5 mg/mL. More water means smaller, easier-to-measure draw volumes. Use the calculator above to find the water volume that gives you a clean, measurable draw for your dose.

1 mg = 1,000 mcg. Many peptide doses are written in micrograms (mcg) — for example, a 250 mcg BPC-157 dose is the same as 0.25 mg. Switch the dose tab to mcg to enter your dose directly without converting.

Use a fresh insulin syringe to draw bacteriostatic water, then inject it slowly along the inner wall of the peptide vial — never directly onto the powder. Do not shake; gently swirl or let it dissolve on its own. Store reconstituted peptides refrigerated and use within the timeframe recommended by your provider.

Most subcutaneous peptide injections use a 1 mL / 100-unit U-100 insulin syringe with a 29–31 gauge, 5/16" (8 mm) needle. This calculator's unit readout is calibrated to a 100-unit syringe — draw to the unit number shown in the result.

Once reconstituted, peptides should be stored in the refrigerator at 2–8°C (36–46°F) and kept away from light. Most reconstituted peptides are stable for 4–6 weeks when refrigerated with bacteriostatic water. Never refreeze a reconstituted peptide — freeze only lyophilized (dry powder) vials.

Bacteriostatic water is sterile water containing 0.9% benzyl alcohol, which inhibits bacterial growth. It is the standard diluent for peptide reconstitution because it keeps multi-dose vials safe for weeks. Do not use regular sterile water or tap water — bacteriostatic water is required for safe multi-use vials.

Yes. Compounded semaglutide and tirzepatide vials work the same way — enter the vial mg, the mL of bacteriostatic water added, and your weekly dose in mg or mcg. The calculator will show your exact draw volume and syringe units. Common starting doses for semaglutide are 0.25 mg/week; tirzepatide typically starts at 2.5 mg/week.

Concentration is how much peptide is dissolved per milliliter of liquid. It is calculated by dividing the vial size by the water added: a 5 mg vial + 2 mL water = 2.5 mg/mL. The higher the concentration, the smaller the volume you need to draw for each dose — which can make injections more comfortable.

Divide the total vial mg by your dose mg. A 5 mg vial at 0.25 mg per dose = 20 doses. The calculator shows this automatically in the "Doses per vial" result. This helps with planning how long a vial will last and when to order your next one.