Peptide Reconstitution Calculator

The Peptide Reconstitution Calculator turns a lyophilized peptide vial into a precise injection plan. Enter the peptide mass on the label, the volume of bacteriostatic water you added, your desired dose, and your insulin syringe size — it returns the concentration in mg/mL, mcg per insulin unit, units to draw, doses per vial, and weeks of supply. It is used by patients on physician-prescribed GLP-1 therapy (semaglutide, tirzepatide, retatrutide) and by researchers and biohackers working with BPC-157, TB-500, GHK-Cu, and other research peptides where accurate self-dosing on a U-100 insulin syringe is critical.

The math is straightforward. Concentration in mg/mL equals peptide milligrams divided by BAC water milliliters. For a standard U-100 insulin syringe (1 mL = 100 units, so 1 unit = 0.01 mL), micrograms per unit equals the mg/mL concentration multiplied by 10. Units to draw equals your dose in mcg divided by mcg per unit. Doses per vial equals total peptide in mcg divided by dose in mcg. Worked example: a 5 mg semaglutide vial reconstituted with 2 mL of bacteriostatic water yields 2.5 mg/mL, which is 25 mcg per insulin unit. For a 250 mcg weekly dose, you draw 10 units on a U-100 syringe, get 20 doses out of the vial, and the vial lasts roughly 20 weeks — though reconstituted peptides should be used within about 28 days refrigerated regardless of remaining doses.