For research & laboratory use only · Not for human consumption · 18+
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Peptide Dosage Calculator

A free peptide dosage and reconstitution calculator. Find out how much bacteriostatic (BAC) water to add to a peptide vial, the resulting concentration, and exactly where to draw each dose on a U-100 insulin syringe.

Peptide in the vial
Amount per draw
Water addedBacteriostatic water already in the vial
Syringe sizeU-100 insulin syringe
Vial sizeHow much liquid the vial can hold

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Draws per vial
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Concentration
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Each unit holds
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    Vial label

    Sized for 40 x 20 mm labels. Save the image and print it from your label app.
    Label style

    This tool does simple arithmetic for reconstituting lyophilized research peptides. It is not medical advice. Double-check every number before use. For research use only.

    Peptide reconstitution FAQ

    How much BAC water should I mix with my peptide?

    Most people use 1-3 mL but there's no single "correct" amount. The volume of bacteriostatic water you add doesn't change how much peptide is in the vial, only how concentrated it is. Our calculator works backwards from your dose: it tells you exactly how much water to add so that every draw lands on a clean mark on your syringe, like 10, 20, or 30 units. The water amount may not be a round number, but you only measure it once, and every draw after that is simple.

    How do I read units on a U-100 insulin syringe?

    A U-100 syringe holds 100 units per 1 mL, so each unit is 0.01 mL and 10 units is 0.1 mL. A 0.3 mL syringe holds 30 units, a 0.5 mL syringe holds 50 units, and a 1 mL syringe holds 100 units.

    How do I work out peptide concentration after reconstitution?

    Divide the milligrams of peptide in the vial by the milliliters of water added. 10 mg in 2 mL is 5 mg/mL, which means each unit on a U-100 syringe holds 0.05 mg (50 mcg).

    What is bacteriostatic water?

    Bacteriostatic (BAC) water is sterile water containing 0.9% benzyl alcohol, a preservative that inhibits bacterial growth. That is why it is commonly used for vials that are drawn from more than once.

    Why does the calculator limit the units I can choose?

    The water has to fit in the vial and each draw has to fit in the syringe. With a 3 mL vial, the calculator only offers unit amounts that need 3 mL of water or less, and never more than the selected syringe holds.

    How many mcg are in a mg?

    1 mg equals 1,000 mcg. Use the mg/mcg switch under Amount per draw and the calculator converts for you.