How much GHK‑Cu per mL of serum?
About 1.25 mg per mL is the standard. Here is how that maps to percentages, teaspoons and strength levels.
The short answer
The standard level is about 1.25 mg of GHK‑Cu per mL of finished serum, or 0.12%. Gentle formulas for the eye area use half that, scalp products and masks use double, and 5 mg per mL (0.5%) is the maximum.
Strength levels
| Level | 5% stock per 100 g | GHK‑Cu | Per mL of serum |
|---|---|---|---|
| Gentle | 1.25 mL | 0.0625% | 0.625 mg |
| Standard | 2.5 mL | 0.125% | 1.25 mg |
| Scalp and hair | 5 mL | 0.25% | 2.5 mg |
| Maximum | 10 mL | 0.5% | 5 mg |
Water-based serums weigh about 1 g per mL, so per gram and per mL come out the same.
Why a stock solution
An ounce of serum at the standard level needs about 37 mg of powder, which a kitchen scale can't weigh. Dissolving the whole gram in 20 mL (4 tsp) of distilled water gives a 5% stock with 50 mg of GHK‑Cu in every mL. Then the dose becomes ⅛ tsp per ounce, and the dosage calculator works out any other batch.
Converting a percentage
1% equals 10 mg per mL. A recipe that calls for 0.1% GHK‑Cu needs 1 mg per mL, or 2 mL of 5% stock per 100 mL of base.
How far one gram goes
At the standard level, about 800 g of serum, or about 27 one-ounce bottles. At the maximum, a quarter of that.
More is not better
The pouch caps it at 2 tsp of stock per 100 g (0.5%). If the serum turns purple or brown, the pH has left the 5 to 7 range or something in the base, like vitamin C or EDTA, is pulling the copper out. Start again in a different base.
Full recipe: how to make a GHK‑Cu serum.
