Peptide Dosage Calculator

When you add bacteriostatic water to a peptide vial, you are not diluting your dose — you are giving yourself a way to measure it. The peptide dissolves evenly throughout the water, creating a uniform concentration expressed as micrograms per milliliter. Every milliliter of that solution contains exactly the same amount of peptide.

A standard U-100 insulin syringe divides 1 mL into 100 equal tick marks — each unit is 0.01 mL. Once you know how concentrated your solution is, the math is a simple ratio: divide your target dose by the concentration to get the volume in mL, then multiply by 100 to convert to units. A 250 mcg dose from a 2,500 mcg/mL solution is 0.1 mL, which is 10 units.

The amount of water you choose changes only your concentration — it does not change the total peptide available. Adding more water makes each unit draw larger and easier to measure precisely. Adding less water makes the solution more concentrated, meaning smaller draws that are harder to measure accurately. Neither choice wastes peptide; both affect your ability to hit the dose with consistent accuracy.

Use this calculator any time you reconstitute a peptide vial from powder. It applies regardless of which peptide you are using — the math is identical for BPC-157, TB-500, Ipamorelin, CJC-1295, or any other lyophilized peptide that requires bacteriostatic water reconstitution.

It is also useful when you change your protocol dose mid-vial. If you have been drawing 250 mcg and your dose changes to 500 mcg, recalculate immediately — the concentration is fixed by the water you already added, and the new draw amount is exactly double the previous one.

Do not use this calculator as a substitute for medical guidance on what dose to take or how frequently to inject. It calculates the draw volume accurately given your inputs, but it has no way to assess whether the dose itself is appropriate for your body weight, health status, or specific protocol. If your prescribed dose produces a draw under 2 units or over 80 units, discuss reconstitution volume with whoever prescribed the protocol rather than adjusting the dose to make the math easier.

The most common mistake is adding water by feel rather than by measurement. If you intended to add 2 mL but added 2.3 mL, your concentration drops proportionally and every draw you take from that vial will be underdosed by about 13 percent. Use a calibrated syringe and note the exact amount.

A second frequent error is confusing the syringe type. U-100 (100 units/mL) and U-50 (50 units/mL) syringes look similar but have different tick-mark spacings. A dose calculated for a U-100 syringe drawn on a U-50 syringe delivers half the intended dose. Always match your syringe type in the calculator to the syringe in your hand.

The third mistake is assuming the powder fully dissolved because the solution looks clear. Some peptides take 15 to 30 minutes to dissolve completely with gentle swirling. Drawing too early from a partially dissolved vial produces inconsistent dose concentrations — the first draw may be weaker, the last draw stronger. Wait for complete dissolution before drawing any dose.

Concentration (mcg/mL) = Vial Size (mcg) / Water Added (mL)

Volume to Draw (mL) = Target Dose (mcg) / Concentration (mcg/mL)

Units to Draw = Volume to Draw (mL) x Syringe Units per mL

For a 5,000 mcg vial with 2 mL water and a 250 mcg dose on a U-100 syringe: Concentration = 5000 / 2 = 2,500 mcg/mL Volume = 250 / 2500 = 0.1 mL Units = 0.1 x 100 = 10 units

Doses per Vial = Vial Size / Target Dose = 5000 / 250 = 20 doses

All three formulas assume the peptide is fully dissolved and uniformly distributed. Incomplete dissolution — common if the vial was shaken instead of gently swirled — creates local concentration gradients that make these calculations unreliable until the solution is homogeneous.

The calculator assumes a perfectly uniform solution, which only holds after complete dissolution. Peptides with poor water solubility — some longer-chain peptides and modified variants — can take over an hour to fully dissolve even with careful swirling. Drawing early from an incompletely dissolved vial introduces a variable concentration that no calculator can correct for. Additionally, if the vial has been drawn from multiple times, reconstitution homogeneity degrades slightly over time in storage; a brief gentle swirl before each draw restores uniformity. At very high concentrations above 5,000 mcg/mL, small errors in water measurement have an outsized effect on the dose ratio — a 0.1 mL error on a 1 mL reconstitution is a 10 percent dose error, but the same 0.1 mL error on a 5 mL reconstitution is only a 2 percent error.