Concentration (mg/mL)

Concentration is the amount of peptide per unit volume of solution, usually stated in milligrams per millilitre. It is fixed at the moment of reconstitution by one division: the mass of peptide in the vial divided by the volume of diluent added. A 10 mg vial with 2 mL of bacteriostatic water is 5 mg/mL; the same vial with 4 mL is 2.5 mg/mL.

Everything downstream follows from that number. A U-100 insulin syringe unit is 0.01 mL, so at 5 mg/mL each unit holds 50 µg and at 2.5 mg/mL each holds 25 µg. Choosing a diluent volume is therefore really choosing how many syringe units a given amount will occupy, and the sensible choice is the one that puts routine draws on easy-to-read marks rather than between them.

Blends add a wrinkle. A vial such as the BPC-157 + TB-500 blend contains two peptides at different masses, so each has its own concentration in the same solution and the arithmetic is done per component. The dosage calculator handles single compounds and blends, and the dosing-math guide explains the working.