How much bacteriostatic water do I add to a GHK-Cu vial?

A common research setup uses 3 mL of bacteriostatic water regardless of vial size. For a 50 mg vial that gives about 16.7 mg/mL; for a 100 mg vial it gives about 33.3 mg/mL. Use the calculator to see the exact units for your vial and dose.

What concentration should I reconstitute GHK-Cu to?

There is no single required concentration — it depends on the vial size and how large a draw you want to read on the syringe. Keeping the water volume at 3 mL for both the 50 mg and 100 mg vial is a common starting point; the calculator shows the resulting units for any combination.

How many units is a 2 mg GHK-Cu dose?

At 3 mL water in a 50 mg vial (16.7 mg/mL), a 2 mg dose is 12 units on a U-100 insulin syringe. At 3 mL water in a 100 mg vial (33.3 mg/mL), the same 2 mg dose is 6 units.

GHK-Cu Reconstitution Calculator: Water & Syringe Math

By PeptCalc — Medically reviewed by David Mansour, MD — Last reviewed July 9, 2026

GHK-Cu is supplied as lyophilized powder and must be reconstituted with a liquid before it can be measured. This reference explains how to convert a GHK-Cu vial and target dose into the exact number of units to draw on a U-100 insulin syringe. It is written for research purposes only and is not medical advice.

What the calculator does

The peptide reconstitution calculator handles the reconstitution math in two directions:

Forward mode — enter vial size, water volume, and target dose → it returns the syringe units to draw.
Reverse mode — enter vial size, target dose, and desired syringe units → it tells you how much water to add.

Both modes work from the same formula: concentration equals mass divided by volume, and dose in units equals dose in volume times 100 (on a U-100 syringe).

Common GHK-Cu vial sizes

Research vials are typically supplied in:

50 mg
100 mg

The calculator supports any vial size. These two are the most frequently seen for GHK-Cu.

Typical research concentration

A common reconstitution setup for GHK-Cu keeps the water volume fixed at 3 mL, regardless of whether the vial is 50 mg or 100 mg. Because the mass differs but the water doesn't, the two vial sizes land at very different concentrations:

Vial size	Water added	Concentration
50 mg	3 mL	≈16.7 mg/mL
100 mg	3 mL	≈33.3 mg/mL

Target dose	Units — 50 mg vial (≈16.7 mg/mL)	Units — 100 mg vial (≈33.3 mg/mL)
1 mg	6 units	3 units
2 mg	12 units	6 units
2.5 mg	15 units	7.5 units
4 mg	24 units	12 units

A half-unit reading (like 7.5 units) is only usable on a syringe marked in half-unit increments. If yours isn't, adjust the water volume in the calculator until the dose lands on a whole tick.

The math

Step 1: Calculate concentration

Concentration = vial mass ÷ water volume

50 mg vial + 3 mL water = 50 ÷ 3 ≈ 16.7 mg/mL
100 mg vial + 3 mL water = 100 ÷ 3 ≈ 33.3 mg/mL

Step 2: Convert dose to volume

Volume (mL) = dose (mg) ÷ concentration (mg/mL)

Example: 2 mg dose at ≈16.7 mg/mL concentration = 2 ÷ 16.7 ≈ 0.12 mL

Step 3: Convert volume to syringe units

On a U-100 insulin syringe, 1 mL = 100 units, so:

Units = volume (mL) × 100

Example: 0.12 mL × 100 ≈ 12 units

The calculator performs these three steps instantly for any vial, water, and dose combination you enter.

Reconstitution process

Gather supplies — GHK-Cu vial, bacteriostatic water, U-100 insulin syringes, alcohol swabs.
Swab both vial stoppers with alcohol.
Draw the calculated water volume (e.g. 3 mL).
Inject slowly down the inside wall of the vial, not directly onto the powder.
Swirl gently — do not shake. Let it dissolve completely.
Verify the concentration matches what you entered in the calculator.

For a detailed walkthrough, see How to Reconstitute Peptides.

Storage

Reconstituted peptide vials are generally stored refrigerated and protected from light. Unreconstituted lyophilized powder is stable at room temperature until the expiration date on the vial. Track the reconstitution date so you know how long a given vial has been mixed.

Why the water volume matters

The same dose can be drawn at very different unit marks depending on how much water goes into the vial:

2 mg dose from a 50 mg vial:

Water added	Concentration	Draw volume	Units
3 mL	≈16.7 mg/mL	≈0.12 mL	12 units
5 mL	10 mg/mL	0.2 mL	20 units

Neither is "wrong" — the math is identical either way. The calculator shows the units for any water volume so you can choose the draw size that's easiest to read accurately on your syringe.

Common mistakes

Confusing mg and mcg. GHK-Cu vials and doses are generally described in milligrams (mg), not micrograms (mcg). Double-check your units before drawing.
Shaking the vial. Swirl gently instead — shaking can degrade the peptide.
Forgetting which concentration you used. If you reconstitute the 50 mg and 100 mg vial at different times, label each one. Drawing units meant for one concentration from a vial mixed at another is a common source of a wrong draw.
Using a non-U-100 syringe. The calculator assumes a standard U-100 insulin syringe (100 units = 1 mL). If your syringe is marked differently, the unit conversion will not match.

Use the calculator

Enter your GHK-Cu vial size, bacteriostatic water volume, and target dose into the peptide reconstitution calculator to see the exact syringe units. Reverse mode also works — enter your target dose and the units you want to draw, and it tells you how much water to add.

The calculator handles the math. This guide explains what the numbers mean and where they come from.