Peptide Reconstitution Mathematics: A Practical Reference

A compact technical reference for the arithmetic of reconstituting lyophilised peptide vials with bacteriostatic water: concentration (C = m / V_w), per-dose draw volume (V_d = D / C), insulin syringe unit conversion for U-100 and U-40 barrels (U = k * D * V_w / m), doses per vial (N = m / D), and the inverse problem of selecting a diluent volume that yields a convenient syringe reading (V_w = U_t * m / (k * D)). Six worked examples are included, each verified against the general formula, covering milligram and microgram dose labelling, the effect of changing diluent volume at a fixed dose, the U-40 versus U-100 misreading error, and rounding to syringe graduation limits. A summary formula card is provided. The document is numerical only. It gives no medical advice and makes no claim about any compound, dose, route, sterility, stability, or legal status. The formulas in section 3 are implemented, with unit handling and syringe rounding, in the open web calculator Peptide Tracker & Calculator, which can be used to check the worked examples against an independent implementation.