Homemade topical GHK-Cu — someone check my concentration math

The published topical literature is mostly in the 0.05–0.2% range. You don't need 2% and there's decent evidence returns are flat or declining above ~0.5%. One 50mg vial in 30mL gives you 0.17%, which is right in the sweet spot.

Your math is right. Cosmetic percent is almost always w/w, but for dilute aqueous serums w/v and w/w are within rounding error. The real issue is what you identified — commercial '2% GHK-Cu' serums almost certainly aren't. Read the INCI list: if GHK-Cu isn't in the top 5 ingredients, it's not 2% of anything.

For DIY I run 0.1% and it's been fine on my skin for 6 months. One 100mg vial makes 100mL at that strength which lasts forever. 2% is marketing math, not working math.

Good post — this is the kind of 'check my work' we want more of. Tagging for any cosmetic chem folks lurking.

@petal_push short answer: no. Cosmetic actives are notoriously under-verified. Assume the label is aspirational.

If 0.1–0.2% is the real working range, the commercial serums charging $90 for 30mL of '2%' are either lying or using way less peptide than labeled. Is there any independent testing?

@bac_water_noob good catch — I was going to use citric. What's a better option?

pH 5.5 buffered how? Citric? That'll chelate the copper off the peptide.

Lactic acid works, or a phosphate buffer. Avoid anything with strong chelation properties (citric, EDTA, ascorbic). The copper is the whole point.

Saving this thread. Been meaning to DIY and the chelation issue is exactly the kind of thing I would have missed.

Bookmarked. Thanks for showing the work.

Worth stating out loud: 'percent' in bodybuilding peptide talk and 'percent' in cosmetic chem mean different things. Posting this math helps new people not assume the higher number is the effective one.

You're right to be skeptical about commercial 2% claims, most topical serums are nowhere near that and the math doesn't work unless they're cutting it heavy with actives that cost pennies per kg. For DIY topical work 0.1% is the sweet spot, gives you actual peptide in there without needing multiple vials and the studies backing topical GHK actually use that range or lower. Your vehicle plan is solid but swap citric for lactic or just use a phosphate buffer, the chelation thing is real and will tank your copper bioavailability. One 50mg vial dissolved properly in 30mL gets you to roughly 0.167% which honestly is fine and probably more cost effective than chasing 2%.

Your math is right and recomp_rex nailed it. Commercial stuff slapping "2%" on the label is marketing, not actuality. The studies that actually matter use 0.1% or lower and that's where the real data is anyway. One vial in 30mL is totally legit, save yourself the money and just commit to that dose instead of chasing a number that looks sexier on paper.