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.

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.

VialWise keeps the calculator paired with a peptide library of 64+ entries, each with primary-source citations, in the iOS app. You can read more about why it exists, or download it on the App Store. For research and educational purposes only.