PeptulatorReconstitution and dosing maths

How the calculator works

Every formula, assumption and rounding rule, in one place, so you can check any answer by hand.

The three steps

Every calculation on this site is the same three divisions, applied in order. The engine that runs them is one JavaScript file, and the tables on every page are generated from the same numbers at build time, so the tool and the pages cannot disagree.

StepFormulaWorked example: 10 mg vial, 2 mL water, 2 mg dose
Concentrationpeptide in the vial ÷ water added10 mg ÷ 2 mL = 5 mg/mL
Draw volumedose ÷ concentration2 mg ÷ 5 mg/mL = 0.4 mL
Syringe unitsvolume × units per mL of the syringe0.4 mL × 100 = 40 units on a U-100 syringe

Reverse mode runs the same steps backwards: units ÷ units per mL gives the volume, and volume × concentration gives the dose.

Syringe scales

Units measure liquid, not drug. The four syringes offered are U-100 at 1 mL, 0.5 mL and 0.3 mL, all of which put 100 units in 1 mL, and U-40 at 1 mL, which puts 40 units in 1 mL. The same 0.4 mL is 40 units on a U-100 barrel and 16 units on a U-40 barrel. The default is U-100, 1 mL, because that is what nearly everything sold for human use is.

Units and conversions

1 mg is 1,000 mcg. Doses entered in mcg are divided by 1,000 before the maths runs. HGH is handled in international units (IU) throughout: the vial strength and the dose are both in IU, so the concentration is IU per mL and the ratio maths is identical. Blends (KLOW, GLOW, the BPC-157 and TB-500 blend, CJC-1295 with ipamorelin) are dosed as the total on the label; the split into each peptide is the label ratio applied to the draw, which is inferred, not measured.

Doses per vial, and how long a vial lasts

Doses per vial is the vial strength divided by the dose, rounded down to a whole number. Vial lasts is that whole number multiplied by the days between doses: 1 for daily, 0.5 for twice daily, 2 for every other day, 1.4 for five days on and two off, 2.33 for three times a week, 3.5 for twice weekly, 7 for weekly. Neither figure accounts for the small amount left in the vial or lost in the syringe.

Cost per dose

Optional. Vial price divided by doses per vial (using the exact, not rounded, number of doses), and vial price divided by the vial strength for the cost per mg or per IU.

Half-life curves

Where a human half-life is documented, the page draws the fraction remaining over four half-lives: remaining = 0.5 to the power of (time ÷ half-life). Where it is not documented, no curve is drawn and the page says so.

Rounding

Units are shown to one decimal place, volumes to three, concentrations to two, and doses to three decimal places in mg (four in the reverse-mode milligram figure) or one in mcg; blend splits are shown to the whole microgram. Rounding happens only at display time; every intermediate step uses the full value.

Warnings

The calculator warns, without changing the answer, when the draw is larger than the syringe holds, when it is under 2 units (hard to read accurately), when more than 5 mL of water is entered (most vials will not take it), when the concentration is over 50 mg/mL, and when a dose sits outside the range commonly reported for that compound. A dose larger than the whole vial is an error, not a warning.

Presets and review

Each compound carries a default vial size, water volume, dose, frequency and reported dose range. These are starting points for the maths, not recommendations. They were last reviewed on 3 September 2026. Always use the strength printed on your own vial.

Testing

The engine has an automated test suite of 143 checks covering the forward and reverse maths, every syringe scale, IU handling, every blend ratio, titration ladders, cost and decay. It runs before every deploy, and a deploy that fails it is not published.

All calculators and charts

Weight management (GLP-1 family)

Growth hormone axis

Repair, skin and blends

Other compounds

Dosage charts and schedules

Tools

Before you use these numbers This is a unit-conversion tool. It turns a vial strength and a water volume into a concentration, a draw volume and a syringe mark. It does not tell you what to take, whether to take it, or whether a compound is safe for you. Most compounds listed are sold for laboratory research and are not approved for human use. Nothing here is medical advice. Dosing decisions belong with a licensed clinician who knows your history. Always check the strength printed on your own vial rather than trusting a preset.