Peptide Calculator

This tool chains three pieces of arithmetic. First, concentration: dividing the vial contents (mg) by the diluent volume (ml) gives mg per milliliter. A 5 mg vial reconstituted with 2 ml of bacteriostatic water yields 5 ÷ 2 = 2.5 mg/ml, and that concentration holds for every drop in the vial. Second, draw volume: a target dose expressed in micrograms is converted to milligrams (1,000 mcg = 1 mg) and divided by the concentration. A 250 mcg target at 2.5 mg/ml works out to 0.25 ÷ 2.5 = 0.1 ml. Third, syringe units: U-100 insulin syringes mark 100 units per milliliter — insulin in the United States is standardized at 100 units/ml, and these syringes are graduated to match that concentration (Donnor & Sarkar, Endotext) — so multiplying the draw volume by 100 converts milliliters to unit markings. In the example, 0.1 ml lands on the 10-unit line.

Concentration is the variable people control at reconstitution time, and it only changes how a dose is measured, never how large it is. More diluent spreads the same peptide across a larger volume, which pushes a small dose onto a bigger, easier-to-read stretch of the syringe barrel; less diluent compresses it into fewer units, where a one-unit reading error represents a larger fraction of the dose.

Where the numbers can mislead

The output is only as good as the inputs. The most common failure is a unit mix-up — entering milligrams where the tool expects micrograms shifts the result a thousandfold. The math also assumes the vial label is accurate: independent testing of research-grade peptides regularly finds quantity and purity that deviate from the label, and no calculator can correct for that. Very small draw volumes (a few units) amplify measurement error, and biological "IU" values cannot be entered here at all because IU measures activity, not mass — see the unit converter for that distinction. Above all, this page does arithmetic on numbers you supply; it has no opinion on whether those numbers are appropriate. Dose decisions belong with a qualified clinician — see the medical disclaimer.

What does "reconstitution" mean? Peptides are usually shipped as a freeze-dried (lyophilized) powder because the dry form is more stable. Reconstitution is the step of dissolving that powder in a liquid — typically bacteriostatic water — so it can be measured by volume. Once dissolved, every milliliter of solution contains a fixed amount of peptide, which is the concentration this calculator computes.

Does adding more water change the dose? No. The amount of peptide in the vial is fixed; water only changes the concentration. Adding more water makes the solution more dilute, so a given dose occupies a larger, easier-to-measure volume. Adding less water concentrates it into a smaller volume. Either way, the same number of micrograms requires the same fraction of the vial.

What is a "unit" on a U-100 syringe? A unit on a U-100 insulin syringe is a volume marking equal to 1/100 of a milliliter (0.01 ml). U-100 syringes are designed around insulin sold at 100 units per milliliter, which is why the barrel is graduated this way. For peptide solutions, the unit markings are simply a convenient volume scale — they say nothing about how much peptide is in that volume until you know the concentration.

Can this calculator tell me what dose to use? No. It performs three divisions and a multiplication — nothing more. It cannot evaluate whether any dose is appropriate, safe, or supported by evidence for any compound or person. Dose selection is a clinical question outside the scope of an arithmetic tool; see the site medical disclaimer.