Peptide reconstitution calculator

How peptide reconstitution math works

Reconstitution is dissolving a powdered peptide in bacteriostatic water so you can measure a precise amount. The math is three steps, and the calculator above does all three — but it helps to understand what it’s doing.

1. Concentration

Concentration is how much peptide sits in each milliliter of solution. Divide the vial size by the water you added:

concentration (mg/mL) = vial mg ÷ BAC water mL

A 30 mg vial reconstituted with 3 mL of bacteriostatic water is 10 mg/mL. Add less water and the same vial gets more concentrated; add more and it gets more dilute.

2. Draw volume

Once you know the concentration, the volume to draw for a given amount is:

draw volume (mL) = target amount ÷ concentration

At 10 mg/mL, a 1 mg amount is 0.1 mL. Amounts are often described in micrograms (mcg) in the research literature while vials are labeled in milligrams (mg) — 1 mg is 1,000 mcg, so the calculator’s mg/mcg toggle re-derives the draw to keep a decimal-point slip from becoming a 1,000× difference.

3. Syringe units

Insulin syringes are marked in units, not milliliters. A U-100 syringe holds 100 units per milliliter, so:

units on a U-100 syringe = draw volume mL × 100

That 0.1 mL draw is 10 units. The calculator rounds to whole units (you can’t measure 16.67 units on a standard syringe) and flags draws that are too small to measure accurately or too large to fit a single syringe. Pick a 30, 50 or 100 IU syringe and the drawing shows the draw on that scale.

Working backward

The reverse mode solves the other direction: pick the draw size you’d like to measure — say a clean 10 units — and the calculator tells you how much bacteriostatic water to add so that draw delivers your target amount.

Blends: several peptides in one vial

Some vials hold two to four peptides together. They share one volume of water, so each has its own concentration (its mg divided by the shared mL), but every draw pulls all of them at once. Set the draw by the amount of one peptide, or by units, and each peptide’s amount in that draw follows from its own concentration:

amount per draw (mg) = peptide mg ÷ water mL × draw mL

For example, 10 mg and 5 mg in 2 mL are 5 mg/mL and 2.5 mg/mL, so a 20-unit draw (0.2 mL) holds 1 mg and 0.5 mg. Because the peptides share the water, each one gives the same number of draws per vial: the water volume divided by the draw volume, 10 draws here.

VialWise keeps the calculator paired with a peptide library of 90+ entries, each with primary-source citations, in the app. You can read more about why it exists, or get it on Google Play. For research and educational purposes only.