How PepGuru Vets Suppliers & Builds Its Tools
PepGuru is a free research-tools and reference hub. This page explains, in plain terms, how we build the calculators, how we rate the suppliers we list, and where we make money — so you can judge our work for yourself. Everything here is educational and research-focused; none of it is medical, legal, or financial advice.
What our calculators actually compute
Every reconstitution calculator does one transparent piece of arithmetic: concentration = vial amount ÷ water added; draw volume = target amount ÷ concentration; and syringe units = draw volume × 100 (on a U-100 insulin syringe, where 100 units = 1 mL). We show the intermediate numbers so you can check them by hand — the tool is a measurement aid, not a black box, and it never recommends an amount.
How we rate suppliers (the tiers)
Our supplier board is tiered S / A / B. We weight four things: independent third-party testing (identity and purity from labs like Janoshik or ACS Labs, with batch COAs a buyer can actually read), transparency (clear labeling, contactable support, honest sourcing), consistency (reship/replacement policies and a track record across batches), and catalogue depth. A supplier with published third-party COAs will always out-rank one relying only on in-house claims.
Why a supplier can move up or down
Tiers are not permanent. A vendor that stops publishing current COAs, changes hands, or accumulates unresolved quality complaints drops. One that adds independent testing and tightens its policies rises. If you have first-hand documentation — a COA, an order experience — that contradicts a placement, that is exactly the kind of evidence that changes it.
Our editorial independence & affiliate disclosure
PepGuru lists Summit Research Supply as its top pick and may earn a referral commission or offer you a discount code when you buy through some links. That relationship is disclosed, not hidden. It does not buy a tier — the vetting criteria above are the same for every vendor, and we list competitors (including EU and other US labs) right alongside Summit so you can compare. Our calculators are free and identical no matter where you buy.
What we are not
We are not a lab, a pharmacy, or a medical provider, and we do not sell products directly. We do not tell anyone to take anything. Compounds referenced across this site are research chemicals sold for laboratory use only. Read the RUO and legality explainer for what that framing means before you buy anything anywhere.
Key takeaways
- Calculators show their arithmetic — concentration, draw volume, and U-100 units — and never recommend a dose.
- Supplier tiers weight independent third-party testing and readable COAs above in-house claims.
- Tiers change with new evidence; documentation that contradicts a placement is welcome.
- We disclose affiliate relationships — they do not buy a tier, and competitors are listed alongside.
