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    PeptideAuthority
    Research reference

    Reconstitution Maths Explainer

    The arithmetic researchers use when reading peptide papers and lab protocols. This page explains how reconstitution maths is calculated, using abstract units only. We do not output personalised doses, suggest peptide-specific quantities, or generate injection protocols.

    Why we no longer publish a dosage calculator

    Previously this page took a peptide name and your weight and returned an injection volume. We removed that because (a) it could not meaningfully distinguish a clinician-supervised licensed prescription from an unsupervised research-chemical purchase, and (b) it was at odds with the rest of the site, which is education and risk intelligence, not procurement support. Reconstitution arithmetic on its own is freely available in published literature; the page below documents the maths so you can read a paper or product insert, not so you can dose an unlicensed substance.

    1. Concentration

    Concentration is mass per unit volume. If a vial contains M mg of dry powder and you add V mL of bacteriostatic water, the resulting concentration is:

    concentration (mg/mL) = M / V

    Worked example. 10 mg of powder reconstituted into 2 mL of water = 5 mg/mL. The choice of V is conventionally made to give a workable per-injection volume; that choice is published in the research protocol, not derived from the patient.

    2. Injection volume per intended dose

    To translate a dose D (mg) into a withdrawal volume V_inj (mL):

    V_inj (mL) = D / concentration
           = D / (M / V)
           = D × V / M

    With insulin syringes (U-100 scale, 1 mL = 100 units) the same quantity expressed in units is:

    V_inj (units) = V_inj (mL) × 100

    In licensed pharmaceutical products (e.g. semaglutide pens) the user does not perform this calculation — the device delivers a pre-set metered dose. The arithmetic above describes the maths researchers use when reading protocols that report doses in mg.

    3. Doses per vial

    doses_per_vial = M / D

    A 10 mg vial dosed at 0.5 mg per injection yields 20 doses. This number determines how long a single reconstituted vial would last in a research protocol, which is relevant for stability calculations (most reconstituted peptides are stable in the fridge for 4–6 weeks, though specific stability is compound-dependent and published in the product literature).

    4. What this arithmetic does NOT tell you

    • Whether the substance is safe or appropriate at any dose for any individual.
    • Whether the product in the vial is what the label says it is (without third-party analytical certificates of analysis).
    • Whether sterile technique, injection site choice, or rotation is being followed.
    • What pharmacokinetic exposure that dose produces in any given person — that requires clinical context, comorbidities, concomitant medication, and supervision.

    For licensed weight-management GLP-1 medicines (Wegovy, Mounjaro, Saxenda) in the UK, the prescriber sets the dose and titration schedule following NICE guidance. The maths above is not a substitute for that clinical decision.

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